CA2756606A1 - Pneumatically powered projectile launcher or air gun - Google Patents
Pneumatically powered projectile launcher or air gun Download PDFInfo
- Publication number
- CA2756606A1 CA2756606A1 CA 2756606 CA2756606A CA2756606A1 CA 2756606 A1 CA2756606 A1 CA 2756606A1 CA 2756606 CA2756606 CA 2756606 CA 2756606 A CA2756606 A CA 2756606A CA 2756606 A1 CA2756606 A1 CA 2756606A1
- Authority
- CA
- Canada
- Prior art keywords
- bolt
- projectile
- receiver
- barrel
- projectile launcher
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41A—FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE
- F41A19/00—Firing or trigger mechanisms; Cocking mechanisms
- F41A19/06—Mechanical firing mechanisms, e.g. counterrecoil firing, recoil actuated firing mechanisms
- F41A19/10—Triggers; Trigger mountings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41A—FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE
- F41A19/00—Firing or trigger mechanisms; Cocking mechanisms
- F41A19/06—Mechanical firing mechanisms, e.g. counterrecoil firing, recoil actuated firing mechanisms
- F41A19/12—Sears; Sear mountings
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41B—WEAPONS FOR PROJECTING MISSILES WITHOUT USE OF EXPLOSIVE OR COMBUSTIBLE PROPELLANT CHARGE; WEAPONS NOT OTHERWISE PROVIDED FOR
- F41B11/00—Compressed-gas guns, e.g. air guns; Steam guns
- F41B11/70—Details not provided for in F41B11/50 or F41B11/60
- F41B11/72—Valves; Arrangement of valves
- F41B11/721—Valves; Arrangement of valves for controlling gas pressure for both firing the projectile and for loading or feeding
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41B—WEAPONS FOR PROJECTING MISSILES WITHOUT USE OF EXPLOSIVE OR COMBUSTIBLE PROPELLANT CHARGE; WEAPONS NOT OTHERWISE PROVIDED FOR
- F41B11/00—Compressed-gas guns, e.g. air guns; Steam guns
- F41B11/60—Compressed-gas guns, e.g. air guns; Steam guns characterised by the supply of compressed gas
- F41B11/62—Compressed-gas guns, e.g. air guns; Steam guns characterised by the supply of compressed gas with pressure supplied by a gas cartridge
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41C—SMALLARMS, e.g. PISTOLS, RIFLES; ACCESSORIES THEREFOR
- F41C23/00—Butts; Butt plates; Stocks
- F41C23/16—Forestocks; Handgrips; Hand guards
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Toys (AREA)
Abstract
A pneumatically powered projectile launcher features a dump chamber containing ported a rear portion of a receiver, a hollow bolt slidably movable in the receiver between a loading and firing positions, and a plunger slidably extending through a rear end of the receiver with a rear end of the plunger in the dump chamber and a front end of the plunger in the receiver. Pressurization of the dump chamber with a gas pushes the plunger against the bolt, and subsequent depressing of a trigger releases the bolt for displacement thereof past the ports of the receiver to communicate the pressurized gas from the dump chamber into the receiver to act against and through the bolt to force a projectile in the barrel through the muzzle end thereof.
Description
PNEUMATICALLY POWERED PROJECTILE LAUNCHER OR AIR GUN
FIELD OF THE INVENTION
The present invention relates generally to pneumatically powered projectile launchers or air guns, and more particularly to a pneumatic launcher or air gun configured to use relatively large projectiles for high muzzle energy at relatively low muzzle velocity.
BACKGROUND OF THE INVENTION
In some other countries, use of firearms for self defense is permissible. In Canada however, the laws are such that you cannot have a firearm stored in a readily accessible manner useful for such purposes.
The definition of a firearm, according to the RCMP is as follows:
"A firearm is a barrelled weapon from which any shot, bullet or other projectile can be discharged and that is capable of causing serious bodily injury or death to a person, and includes any frame or receiver of such a barrelled weapon, as well as anything that can be adapted for use as a firearm."
(Source: http://www.rcmp-gre.gc.ca/cfp-pcaf/faq/index-eng.htm).
Exceptions to this definition include some air guns, with certain performance characteristics and the manner of use of the air gun being used to determine whether they qualify as firearms, as follows:
Air guns that are firearms for purposes of both the Firearms Act and the Criminal Code.
"These are air guns with both a high muzzle velocity (greater than 2 152.4 meters or 500 feet per second) and a high muzzle energy (greater than 5.7 joules or 4.2 foot-pounds). The "muzzle velocity" is the speed of a projectile at the instant it leaves the muzzle of a gun, normally expressed in metres per second or feet per second. The "muzzle energy" is the energy of a projectile at the instant it /eaves the muzzle of a gun, expressed in joules or foot-pounds. Air guns need to meet both standards to be classified as firearms for purposes of the Firearms Act.
Air guns that meet the Criminal Code definition of a firearm, but that are deemed not to be firearms for certain purposes of the Firearms Act and Criminal Code.
These are air guns with a maximum muzzle velocity of 152.4 meters or 500 feet per second and/or a maximum muzzle energy of 5.7 joules or 42 foot pounds.
Such air guns are exempt from licensing, registration, and other requirements under the Firearms Act, and from penalties set out in the Criminal Code for possessing a firearm without a valid licence or registration certificate. However, they are considered to be firearms under the Criminal Code if they are used to commit a crime. Anyone who uses such an air gun to commit a crime faces the same penalties as someone who uses a regular firearm.
The simple possession, acquisition and use of these air guns for lawful purposes is regulated more by provincial and municipal laws and by-laws than by federal law. For example, some provinces may have set a minimum age for acquiring such an air gun. For more information, please contact your local or provincial authorities.
These air guns are exempt from the specific safe storage, transportation and handling requirements set out in the regulations supporting the Firearms Act. However, the Criminal Code requires that reasonable precautions be taken to use, carry, handle, store, transport, and shipped them in a safe and secure manner.
(Source: http://www.rcmp-grc.gc.ca/cfp-pcaf/fs-fd/air gun-arme_air-eng.htm).
Accordingly, having air guns with a muzzle velocity of less than 500 feet per second and/or a muzzle energy of 4.2 foot-pounds or less are not considered firearms for the purposes of the Firearms Act and the Criminal Code, so long as they are not used to commit a crime.
This has led the applicant to create a personal protection device that meets the performance criteria for being an airgun without qualification as a firearm, preferably with a muzzle velocity below 500 fps (feet per second) but using HPA
(high pressure air) to provide sufficient muzzle energy for ample stopping power against an attacker. As a non-firearm, the air gun would thus be excluded from the specific safe storage, transportation and handling requirements set out in the regulations supporting the Firearms Act, in which case storage in a ready-to-defend manner would not be an offence under that act, which requires that firearms be stored in unloaded condition and locked away or rendered inoperable.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:
Figure 1 is a side elevational view of an air gun according to the present invention.
Figure 2 is a partial cross-sectional view of the air gun of Figure 1 as a first ball-shaped projectile is propelled through the barrel and the bolt returns to its default position allowing automatic loading of a second ball-shaped projectile from a magazine.
Figure 3 is a partial cross-sectional view of the air gun, with biasing springs omitted for ease of illustration, before the trigger is depressed to advance the bolt from its default position and propel the first projectile of Figure 2 down the barrel.
Figure 4 is a partial cross-sectional view of the air gun, with the biasing springs again omitted for ease of illustration, as the first projectile of Figure 3 is propelled down the barrel from the advanced bolt, which temporarily blocks the loading of the second projectile from the magazine.
Figure 5 is a partial cross-sectional view of the air gun showing the condition of the trigger assembly when the air gun is in a ready to fire condition with a fully pressurized dump tank.
Figure 6 is a partial cross-sectional view of the air gun as the trigger is initially depressed from the ready to fire condition of Figure 5 to withdraw a stop member or bolt catch from the bolt.
Figure 7 is a partial cross-sectional view of the air gun as the trigger remains in the depressed condition of Figure 6 and the bolt is driven forward by air from the dump tank and the stop member is forced out of engagement with the trigger by a spring.
Figure 8 is a partial cross-sectional view of the air gun as the trigger remains in the depressed condition of Figure 7 and the bolt has been spring-returned to its default retracted position, where it is engaged by the stop member to maintain this position until a subsequent pulling of the trigger with the dump chamber pressurized.
DETAILED DESCRIPTION
Structure Figure 1 shows an air gun 10 of the present invention, featuring a barrel 12 having a muzzle end 14 and an opposing breech end 16, a receiver 18 disposed at the breech end 16 of the barrel, a dump chamber 20 containing a rear end of the receiver 18 opposite the barrel 12, a hand grip 22 depending downward from the underside of the dump chamber 20, a magazine 24 releasably attached to and depending downward from the underside of the barrel 12 at the breech end 16 thereof, a trigger assembly 26 attached to the underside of the receiver 18 and presenting a trigger 28 depending downwardly away therefrom in front of the hand grip 22, and a high pressure air (H PA) tank 30 attached at the bottom of the hand grip.
Turning to Figure 2, a hollow bolt 32 has a larger outer diameter cylindrical portion 34 residing within a cylindrical interior bore of the receiver 18 and a smaller outer diameter cylindrical portion 36 extending from the larger diameter portion 34 partially into the barrel 12 through the breach end 16 thereof. The hollow bolt features an axial through-bore 32a running through it, from its larger diameter rear end 34a nearest a closed rear wall 38 of the receiver to its opposing smaller diameter front end 36a in the breech of the barrel 12. The bore 32a of the bolt is cylindrical from the bolt's rear end 34a to near the bolt's front end 36a, where the bore then flares smoothly outward to the front end of the bolt. A compression spring 40 coils around the smaller diameter portion 36 of the bolt 32 between the breech end 16 of the barrel 12, which is located a short distance inside the front end of the receiver, and the shoulder defined on the exterior of the bolt at the transition between the large and small diameter portions 34, 36, thereby biasing the bolt toward the closed rear wall 38 of the receiver 18.
Just outside the front of the receiver 18, a cylindrical collar 42 depends perpendicularly downward from the underside of the barrel in a manner encircling a hole or opening 44 therein in order to concentrically receive the upper portion of the tubular body 46 of the magazine 24 to position the open upper end of the magazine tube 46 adjacent the opening 44 in the barrel. Mechanisms for securing a magazine in this received position nested inside the magazine collar 42 of the barrel are known, and thus not shown or described herein. Inside the magazine, a coiled compression spring 48 is disposed between the closed bottom 50 of the magazine tube 46 and a plurality of solid metal-balls stacked atop the spring, thus forcing the uppermost one of the balls into the barrel 12 adjacent the breech end thereof.
Figure 2 shows the magazine in a nearly consumed condition, having only one metal ball 52 remaining therein. In addition to storing the round-ball projectiles, the magazine also doubles as a fore grip for additional support of the air gun by the operator's second had at a distance ahead of the main hand grip 22.
The dump chamber 20 has its front end fixed to the receiver 18 in a manner sealed therearound at an axially intermediate therealong to enclose a rear portion of the receiver within the hollow interior of the dump chamber 20. This rear portion of the receiver includes the closed rear wall 38 and a series of circumferential ports or openings 54 (Fig. 4) located in the peripheral wall of the receiver 18 a short distance ahead of the closed rear wall 38 to allow fluid communication between the interior space of the receiver 18 and the dump tank interior 56 containing the rear portion of the receiver. Except for these openable and closable ports 54, the interior of the receiver is otherwise sealed off from the interior of the dump chamber 20.
An axial bore through the closed end 38 of the receiver 18 slidably supports and seals with an intermediate portion of a plunger 58 having an enlarged head or stop 60 at is rear end, and similar stop or flange 62 near its front end. The rear end stop 60 of the plunger 58 resides in the outside the receiver 18 in the interior 56 of the dump chamber 20. When the plunger 58 slides toward a forwardmost position, =
limited by contact of the rear stop 60 against the outside the receiver's closed rear wall 38, the front end 62 of the plunger passes by the rearmost extent of the ports 54. In the opposite direction, the plunger 58 can slide into a rearmost position in which the stop 62 at the front end of the plunger 58 becomes seated in a recess 64 provided in the otherwise-flat inner surface of the receiver's closed rear wall 38 by a 8 counterbored end of the plunger-receiving bore. Contact of the shoulder defined between the front stop 62 of the plunger and the smaller-diameter intermediate portion of the plunger 58 with the corresponding shoulder defined by the inner end of the counter-bore 64 defines the rearmost position of the plunger, where the front stop 62 is at least partially recessed in this counterbore 64 to minimize or avoid any extension of the plunger 58 into the interior space of the receiver. Figure 3 shows the plunger 58 in its rearmost position, and Figure 4 shows it in its forwardmost position.
An inlet valve 66 located at the rear of the dump chamber 20 features a hollow cylinder 68 having a first open end 70 open to the exterior of the dump chamber 20 at the rear wall thereof, an opposing closed end 72, and a series of circumferential ports or openings 74 extending radially through the peripheral wall of the cylinder adjacent the closed end wall 72 thereof. Opening and closing of the valve 66 is achieved by a cylindrical sleeve 76 slidably disposed around the exterior of the cylinder 68. The cylinder 68 extends into an open end of the sleeve 76 toward an opposing closed end 78 thereof. The sleeve 76 features a series of circumferential ports or holes 80 extending radially through the peripheral wall of the sleeve 76 near the closed end wall 78 thereof. The outer end of the cylinder located at the rear wall of the dump chamber 20 is adapted in a conventional manner for coupling to the outlet valve of a high pressure air tank so that the tank feeds into the internal bore of channel of the cylinder. In the illustrated embodiment, the tank is connected at the bottom of the grip, and thus is routed to the dump chamber via internal or external hose or piping (not shown). Alternatively, the HPA
tank could be attached at the back of the dump chamber. The illustrated position may be optimal, as the end of the tank can be used as a buttstock and placed against the shoulder, aligning the barrel fairly close to the user's sight line. Also having the tank behind the hand grip may help balance the device.
Sliding seals (not shown) are provided around the periphery of the cylinder on opposing sides of the ports 74 therein to seal against the surrounding inner peripheral surface of the sleeve 78 while allowing sliding between the two components. Thus, when the closed end of the cylinder resides between the sleeve ports 80 and the closed end 78 of the sleeve 76 (as shown in Fig. 3), the ports of the two pieces are in fluid communication, thereby opening the valve in order to fluidly communicate the bore of the cylinder 68 with the surrounding interior of the dump chamber. When the closed end of the cylinder is located on the side of the sleeve ports 80 opposite the closed end of the sleeve 78 (as shown in Fig. 4), the valve is closed, sealing off the cylinder, and the pressurized air tank coupled therewith, from the dump chamber interior. With reference to Figure 2, a compression spring 82 disposed between the open end of the sleeve 76 and the rear wall of the dump chamber biases the sleeve into the valve-closing position.
The trigger assembly features a first pin 84 on which the trigger 28, and an extension 86 defined integrally therewith as part of a same unitary body, are pivotally carried for rotation about an axis perpendicular to the barrel axis along which the bolt 32 is slides in the receiver and breech end of the barrel. The extension 86 extends forwardly from the first pin 84, while the trigger 28 depends downwardly from the first pin 84 to extend outward from a housing 88 of the trigger assembly, on which the first 84 pin is supported at a side wall of the housing 88. A compression spring 90 is disposed between a bottom of the trigger extension 86 and a bottom wall of the trigger housing 88 to force the extension upward, and thereby bias the trigger forward into its normal default position. A slide member 92 is slidably disposed within a slot or channel extending along the trigger extension 86 from the front end thereof. A compression spring 94 disposed between the slide member 92 and the closed end of the slot or channel furthest from the front end of the trigger extension in order to bias the front end of the slide member to a position jutting past the front end of the extension. The travel of the slide member in this direction is limited by cooperation of a pin 96 jutting from a side of the slot or channel of the trigger extension with a slot 98 in the slide member. The slide member 92 cooperates with a stop member 100 of the trigger assembly to move the stop member out of a position engaging against the bolt 32 when the trigger is depressed toward the hand grip 22.
The stop member 100 is an elongated piece having a lower end disposed within the housing 88 of the trigger assembly 26 in front of the trigger extension 86 and an upper end reaching into the receiver 18 via a hole in the bottom thereof and a notch 102 aligned with that hole in the bottom of the barrel 12 at the breech end 16 thereof. A cross-pin 104 in the hole in the bottom of the receiver pivotally supports the stop member 100 for rotation about an axis parallel to the pivot axis of the trigger 28, and the opening 105 in the stop member through which the cross-pin 104 extends is elongated in the longitudinal direction of the stop member to allow limited sliding thereof up and down on the cross-pin 104 to change how far the stop member projects upward into the receiver 18. The bottom end of the stop member 100 features a catch 106 that presents an upward facing ledge or shoulder jutting toward the pivot pin 84 of the trigger. A compression spring 108 disposed between the bottom wall of the trigger assembly housing 88 and the lower end of the stop member 100 acts upward and forward thereon, tending to slide the stop member upward on the cross-pin 84 and pivot the bottom end of the stop member forward about the cross-pin 86. A recess or notch 110 in the underside of the bolt 32 hear the front end 36a thereof receives the top end of the stop member 100 when the stop member is biased into its uppermost position in the receiver 18 and the bolt 32 is biased into its rearmost position nearest the closed rear wall of the receiver, which places the recess 110 over the notch 102 at the breech end 16 of the barrel 12.
Operation Having described the structure of the air gun, its operation will now be described.
Coil spring 40 biases the bolt 32 into a rearward position near the closed rear end 38 of the receiver. With the bolt in this position, a pair of circumferential seals (not shown) are engaged between the large diameter portion 34 of the bolt 32 and the surrounding inner peripheral wall of the receiver on opposite sides of the ports 54 in this wall of the receiver, thereby sealing off the receiver interior from the dump chamber 20. The seals are located on the bolt, so as to slide along the receiver during movement of the bolt. This rearward position of the bolt defines a loading position, as the front end 36a of the bolt 32 is situated just behind the opening 44 12 through which metal balls are fed into the barrel by the magazine. With the trigger 28 and the stop member 100 biased into their default positions by the respective coil springs 90, 108, as shown in Figure 5, the top end of the stop member 100 projects into the recess 110 in the underside of the bolt 32, and the catch 106 at the bottom of the stop member catches under the forwardmost end of the slide member 92 exposed at the front of the trigger extension 86. The top end of the stop member abuts against the end of the bolt recess 110 nearest the larger diameter rear end 34a of the bolt, thereby blocking pivotal movement of the stop member 100 on the cross-pin 104 in the direction that would pull the catch 106 forwardly out from under the slide member 92 of the trigger extension 86. The raised position of the stop member 100 to engage into the recess 110 in the exterior of the bolt prevents any forward movement of the bolt 32. The forcing of the bolt 32 into its rearward position by the respective spring 40 causes the rear end 34a of the bolt 32 to push reward on the plunger 58, which in turn is long enough to push rearward on the closure sleeve 78 of the inlet valve against the spring 82 pushing forward thereagainst. The bolt spring 40 is stronger than the valve spring 82, and so this biasing of the bolt into the rearward loading position overcomes the bias of the valve spring 82 to move the valve closure sleeve 76 into the open position allowing airflow into the dump chamber.
With the HPA tank 30 connected, high pressure thus air flows into the dump chamber 20 through the inlet valve 66 contained inside the dump chamber, which may be regulated in a known manner to fill to a predetermined pressure. Once the pressure inside the dump chamber 20 reaches the predetermined value, the device is ready to fire the metal ball that has been automatically loaded into the barrel in front of the bolt by the magazine. When the trigger 28 is pulled rearward from the ready to fire condition of Figure 5, the catch 106 of the stop member 100 is pulled downward by the slide member 92 of the trigger extension 86 under the pivoting of the trigger and extension about the respective pin 84, thereby withdrawing the top end of the stop member 100 from the recess 110 of the bolt and thus unlocking the bolt from its rearward loading position, as shown in Figure 6. Initially the bolt is held in this rearward loading position by the respective spring 40. However, the high pressure air in the dump tank acts on the rear end of the plunger 58, pushing the plunger 58 forward in the dump tank. To cause this desired directional movement of the plunger 58, the rear end 58a of the plunger has a reduced diameter smaller than both the rear stop 60 located adjacent that end, and the intermediate portion of the plunger between the two stops 60, 62. This way, there is a greater surface area for the dump tank pressure to act against in the forward direction at the rear face of the rear stop 60 than in the rearward direction at the front face of the rear stop. The extension of this reduced-diameter rear end of the plunger past the rear stop creates a space in which the dump chamber air pressure can act between the plungers rear stop 60 and the closed end 78 of the inlet valve sleeve 76.
The inlet valve sleeve 76 follows the plunger 58 under the action of the respective spring 82, so that under sufficient forward travel of the plunger 58, the sleeve moves into the closed position turning off the inlet valve 66, thereby cutting off the supply of high pressure air to the dump chamber from the HPA tank 30.
The forward motion of the plunger 68 also pushes the bolt 32 forward in the receiver 18, so that simultaneous to, or just after, this shutting off of the inlet valve, the rear end of the bolt reaches the ports 54 in the receiver's peripheral wall, opening the ports as the seal near the rear end of the bolt moves past the rearmost extent of the ports.
This opening of these ports or vent holes in the receiver wall allows the HPA
contained in the dump chamber to rapidly expand through these vent holes, into the receiver, forcing the bolt to the fully forward position, and flowing through the axial bore in the middle of the bolt into the barrel, pushing the ball-shaped projectile out of the barrel at the muzzle. When in its rearward loading position, the front end of the bolt resides immediately behind the location where the magazine opens to the barrel, and so the initial movement of the bolt under the action of the plunger immediately begins to close off the magazine opening to the barrel above, and so the subsequent movement of the bolt under the introduction of the high pressure air to the receiver quickly completes this closure of the magazine in an effectively instantaneous manner to close of the magazine before any high pressure air can gain entry thereto. Circumferential seals (not shown) on the interior wall of the barrel on opposite sides of the magazine opening provide an air tight fit between the bolt and the barrel.
As described above, the stop member is spring loaded for two types of biased motion, a rotational motion and an upward sliding motion. Once it has been pulled downward by the trigger far enough to release the bolt, as shown in Figure 6, the stop member will rotate (clockwise in Figs. 3 & 4, counterclockwise in Figs.
FIELD OF THE INVENTION
The present invention relates generally to pneumatically powered projectile launchers or air guns, and more particularly to a pneumatic launcher or air gun configured to use relatively large projectiles for high muzzle energy at relatively low muzzle velocity.
BACKGROUND OF THE INVENTION
In some other countries, use of firearms for self defense is permissible. In Canada however, the laws are such that you cannot have a firearm stored in a readily accessible manner useful for such purposes.
The definition of a firearm, according to the RCMP is as follows:
"A firearm is a barrelled weapon from which any shot, bullet or other projectile can be discharged and that is capable of causing serious bodily injury or death to a person, and includes any frame or receiver of such a barrelled weapon, as well as anything that can be adapted for use as a firearm."
(Source: http://www.rcmp-gre.gc.ca/cfp-pcaf/faq/index-eng.htm).
Exceptions to this definition include some air guns, with certain performance characteristics and the manner of use of the air gun being used to determine whether they qualify as firearms, as follows:
Air guns that are firearms for purposes of both the Firearms Act and the Criminal Code.
"These are air guns with both a high muzzle velocity (greater than 2 152.4 meters or 500 feet per second) and a high muzzle energy (greater than 5.7 joules or 4.2 foot-pounds). The "muzzle velocity" is the speed of a projectile at the instant it leaves the muzzle of a gun, normally expressed in metres per second or feet per second. The "muzzle energy" is the energy of a projectile at the instant it /eaves the muzzle of a gun, expressed in joules or foot-pounds. Air guns need to meet both standards to be classified as firearms for purposes of the Firearms Act.
Air guns that meet the Criminal Code definition of a firearm, but that are deemed not to be firearms for certain purposes of the Firearms Act and Criminal Code.
These are air guns with a maximum muzzle velocity of 152.4 meters or 500 feet per second and/or a maximum muzzle energy of 5.7 joules or 42 foot pounds.
Such air guns are exempt from licensing, registration, and other requirements under the Firearms Act, and from penalties set out in the Criminal Code for possessing a firearm without a valid licence or registration certificate. However, they are considered to be firearms under the Criminal Code if they are used to commit a crime. Anyone who uses such an air gun to commit a crime faces the same penalties as someone who uses a regular firearm.
The simple possession, acquisition and use of these air guns for lawful purposes is regulated more by provincial and municipal laws and by-laws than by federal law. For example, some provinces may have set a minimum age for acquiring such an air gun. For more information, please contact your local or provincial authorities.
These air guns are exempt from the specific safe storage, transportation and handling requirements set out in the regulations supporting the Firearms Act. However, the Criminal Code requires that reasonable precautions be taken to use, carry, handle, store, transport, and shipped them in a safe and secure manner.
(Source: http://www.rcmp-grc.gc.ca/cfp-pcaf/fs-fd/air gun-arme_air-eng.htm).
Accordingly, having air guns with a muzzle velocity of less than 500 feet per second and/or a muzzle energy of 4.2 foot-pounds or less are not considered firearms for the purposes of the Firearms Act and the Criminal Code, so long as they are not used to commit a crime.
This has led the applicant to create a personal protection device that meets the performance criteria for being an airgun without qualification as a firearm, preferably with a muzzle velocity below 500 fps (feet per second) but using HPA
(high pressure air) to provide sufficient muzzle energy for ample stopping power against an attacker. As a non-firearm, the air gun would thus be excluded from the specific safe storage, transportation and handling requirements set out in the regulations supporting the Firearms Act, in which case storage in a ready-to-defend manner would not be an offence under that act, which requires that firearms be stored in unloaded condition and locked away or rendered inoperable.
SUMMARY OF THE INVENTION
According to a first aspect of the invention there is provided BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary embodiment of the present invention:
Figure 1 is a side elevational view of an air gun according to the present invention.
Figure 2 is a partial cross-sectional view of the air gun of Figure 1 as a first ball-shaped projectile is propelled through the barrel and the bolt returns to its default position allowing automatic loading of a second ball-shaped projectile from a magazine.
Figure 3 is a partial cross-sectional view of the air gun, with biasing springs omitted for ease of illustration, before the trigger is depressed to advance the bolt from its default position and propel the first projectile of Figure 2 down the barrel.
Figure 4 is a partial cross-sectional view of the air gun, with the biasing springs again omitted for ease of illustration, as the first projectile of Figure 3 is propelled down the barrel from the advanced bolt, which temporarily blocks the loading of the second projectile from the magazine.
Figure 5 is a partial cross-sectional view of the air gun showing the condition of the trigger assembly when the air gun is in a ready to fire condition with a fully pressurized dump tank.
Figure 6 is a partial cross-sectional view of the air gun as the trigger is initially depressed from the ready to fire condition of Figure 5 to withdraw a stop member or bolt catch from the bolt.
Figure 7 is a partial cross-sectional view of the air gun as the trigger remains in the depressed condition of Figure 6 and the bolt is driven forward by air from the dump tank and the stop member is forced out of engagement with the trigger by a spring.
Figure 8 is a partial cross-sectional view of the air gun as the trigger remains in the depressed condition of Figure 7 and the bolt has been spring-returned to its default retracted position, where it is engaged by the stop member to maintain this position until a subsequent pulling of the trigger with the dump chamber pressurized.
DETAILED DESCRIPTION
Structure Figure 1 shows an air gun 10 of the present invention, featuring a barrel 12 having a muzzle end 14 and an opposing breech end 16, a receiver 18 disposed at the breech end 16 of the barrel, a dump chamber 20 containing a rear end of the receiver 18 opposite the barrel 12, a hand grip 22 depending downward from the underside of the dump chamber 20, a magazine 24 releasably attached to and depending downward from the underside of the barrel 12 at the breech end 16 thereof, a trigger assembly 26 attached to the underside of the receiver 18 and presenting a trigger 28 depending downwardly away therefrom in front of the hand grip 22, and a high pressure air (H PA) tank 30 attached at the bottom of the hand grip.
Turning to Figure 2, a hollow bolt 32 has a larger outer diameter cylindrical portion 34 residing within a cylindrical interior bore of the receiver 18 and a smaller outer diameter cylindrical portion 36 extending from the larger diameter portion 34 partially into the barrel 12 through the breach end 16 thereof. The hollow bolt features an axial through-bore 32a running through it, from its larger diameter rear end 34a nearest a closed rear wall 38 of the receiver to its opposing smaller diameter front end 36a in the breech of the barrel 12. The bore 32a of the bolt is cylindrical from the bolt's rear end 34a to near the bolt's front end 36a, where the bore then flares smoothly outward to the front end of the bolt. A compression spring 40 coils around the smaller diameter portion 36 of the bolt 32 between the breech end 16 of the barrel 12, which is located a short distance inside the front end of the receiver, and the shoulder defined on the exterior of the bolt at the transition between the large and small diameter portions 34, 36, thereby biasing the bolt toward the closed rear wall 38 of the receiver 18.
Just outside the front of the receiver 18, a cylindrical collar 42 depends perpendicularly downward from the underside of the barrel in a manner encircling a hole or opening 44 therein in order to concentrically receive the upper portion of the tubular body 46 of the magazine 24 to position the open upper end of the magazine tube 46 adjacent the opening 44 in the barrel. Mechanisms for securing a magazine in this received position nested inside the magazine collar 42 of the barrel are known, and thus not shown or described herein. Inside the magazine, a coiled compression spring 48 is disposed between the closed bottom 50 of the magazine tube 46 and a plurality of solid metal-balls stacked atop the spring, thus forcing the uppermost one of the balls into the barrel 12 adjacent the breech end thereof.
Figure 2 shows the magazine in a nearly consumed condition, having only one metal ball 52 remaining therein. In addition to storing the round-ball projectiles, the magazine also doubles as a fore grip for additional support of the air gun by the operator's second had at a distance ahead of the main hand grip 22.
The dump chamber 20 has its front end fixed to the receiver 18 in a manner sealed therearound at an axially intermediate therealong to enclose a rear portion of the receiver within the hollow interior of the dump chamber 20. This rear portion of the receiver includes the closed rear wall 38 and a series of circumferential ports or openings 54 (Fig. 4) located in the peripheral wall of the receiver 18 a short distance ahead of the closed rear wall 38 to allow fluid communication between the interior space of the receiver 18 and the dump tank interior 56 containing the rear portion of the receiver. Except for these openable and closable ports 54, the interior of the receiver is otherwise sealed off from the interior of the dump chamber 20.
An axial bore through the closed end 38 of the receiver 18 slidably supports and seals with an intermediate portion of a plunger 58 having an enlarged head or stop 60 at is rear end, and similar stop or flange 62 near its front end. The rear end stop 60 of the plunger 58 resides in the outside the receiver 18 in the interior 56 of the dump chamber 20. When the plunger 58 slides toward a forwardmost position, =
limited by contact of the rear stop 60 against the outside the receiver's closed rear wall 38, the front end 62 of the plunger passes by the rearmost extent of the ports 54. In the opposite direction, the plunger 58 can slide into a rearmost position in which the stop 62 at the front end of the plunger 58 becomes seated in a recess 64 provided in the otherwise-flat inner surface of the receiver's closed rear wall 38 by a 8 counterbored end of the plunger-receiving bore. Contact of the shoulder defined between the front stop 62 of the plunger and the smaller-diameter intermediate portion of the plunger 58 with the corresponding shoulder defined by the inner end of the counter-bore 64 defines the rearmost position of the plunger, where the front stop 62 is at least partially recessed in this counterbore 64 to minimize or avoid any extension of the plunger 58 into the interior space of the receiver. Figure 3 shows the plunger 58 in its rearmost position, and Figure 4 shows it in its forwardmost position.
An inlet valve 66 located at the rear of the dump chamber 20 features a hollow cylinder 68 having a first open end 70 open to the exterior of the dump chamber 20 at the rear wall thereof, an opposing closed end 72, and a series of circumferential ports or openings 74 extending radially through the peripheral wall of the cylinder adjacent the closed end wall 72 thereof. Opening and closing of the valve 66 is achieved by a cylindrical sleeve 76 slidably disposed around the exterior of the cylinder 68. The cylinder 68 extends into an open end of the sleeve 76 toward an opposing closed end 78 thereof. The sleeve 76 features a series of circumferential ports or holes 80 extending radially through the peripheral wall of the sleeve 76 near the closed end wall 78 thereof. The outer end of the cylinder located at the rear wall of the dump chamber 20 is adapted in a conventional manner for coupling to the outlet valve of a high pressure air tank so that the tank feeds into the internal bore of channel of the cylinder. In the illustrated embodiment, the tank is connected at the bottom of the grip, and thus is routed to the dump chamber via internal or external hose or piping (not shown). Alternatively, the HPA
tank could be attached at the back of the dump chamber. The illustrated position may be optimal, as the end of the tank can be used as a buttstock and placed against the shoulder, aligning the barrel fairly close to the user's sight line. Also having the tank behind the hand grip may help balance the device.
Sliding seals (not shown) are provided around the periphery of the cylinder on opposing sides of the ports 74 therein to seal against the surrounding inner peripheral surface of the sleeve 78 while allowing sliding between the two components. Thus, when the closed end of the cylinder resides between the sleeve ports 80 and the closed end 78 of the sleeve 76 (as shown in Fig. 3), the ports of the two pieces are in fluid communication, thereby opening the valve in order to fluidly communicate the bore of the cylinder 68 with the surrounding interior of the dump chamber. When the closed end of the cylinder is located on the side of the sleeve ports 80 opposite the closed end of the sleeve 78 (as shown in Fig. 4), the valve is closed, sealing off the cylinder, and the pressurized air tank coupled therewith, from the dump chamber interior. With reference to Figure 2, a compression spring 82 disposed between the open end of the sleeve 76 and the rear wall of the dump chamber biases the sleeve into the valve-closing position.
The trigger assembly features a first pin 84 on which the trigger 28, and an extension 86 defined integrally therewith as part of a same unitary body, are pivotally carried for rotation about an axis perpendicular to the barrel axis along which the bolt 32 is slides in the receiver and breech end of the barrel. The extension 86 extends forwardly from the first pin 84, while the trigger 28 depends downwardly from the first pin 84 to extend outward from a housing 88 of the trigger assembly, on which the first 84 pin is supported at a side wall of the housing 88. A compression spring 90 is disposed between a bottom of the trigger extension 86 and a bottom wall of the trigger housing 88 to force the extension upward, and thereby bias the trigger forward into its normal default position. A slide member 92 is slidably disposed within a slot or channel extending along the trigger extension 86 from the front end thereof. A compression spring 94 disposed between the slide member 92 and the closed end of the slot or channel furthest from the front end of the trigger extension in order to bias the front end of the slide member to a position jutting past the front end of the extension. The travel of the slide member in this direction is limited by cooperation of a pin 96 jutting from a side of the slot or channel of the trigger extension with a slot 98 in the slide member. The slide member 92 cooperates with a stop member 100 of the trigger assembly to move the stop member out of a position engaging against the bolt 32 when the trigger is depressed toward the hand grip 22.
The stop member 100 is an elongated piece having a lower end disposed within the housing 88 of the trigger assembly 26 in front of the trigger extension 86 and an upper end reaching into the receiver 18 via a hole in the bottom thereof and a notch 102 aligned with that hole in the bottom of the barrel 12 at the breech end 16 thereof. A cross-pin 104 in the hole in the bottom of the receiver pivotally supports the stop member 100 for rotation about an axis parallel to the pivot axis of the trigger 28, and the opening 105 in the stop member through which the cross-pin 104 extends is elongated in the longitudinal direction of the stop member to allow limited sliding thereof up and down on the cross-pin 104 to change how far the stop member projects upward into the receiver 18. The bottom end of the stop member 100 features a catch 106 that presents an upward facing ledge or shoulder jutting toward the pivot pin 84 of the trigger. A compression spring 108 disposed between the bottom wall of the trigger assembly housing 88 and the lower end of the stop member 100 acts upward and forward thereon, tending to slide the stop member upward on the cross-pin 84 and pivot the bottom end of the stop member forward about the cross-pin 86. A recess or notch 110 in the underside of the bolt 32 hear the front end 36a thereof receives the top end of the stop member 100 when the stop member is biased into its uppermost position in the receiver 18 and the bolt 32 is biased into its rearmost position nearest the closed rear wall of the receiver, which places the recess 110 over the notch 102 at the breech end 16 of the barrel 12.
Operation Having described the structure of the air gun, its operation will now be described.
Coil spring 40 biases the bolt 32 into a rearward position near the closed rear end 38 of the receiver. With the bolt in this position, a pair of circumferential seals (not shown) are engaged between the large diameter portion 34 of the bolt 32 and the surrounding inner peripheral wall of the receiver on opposite sides of the ports 54 in this wall of the receiver, thereby sealing off the receiver interior from the dump chamber 20. The seals are located on the bolt, so as to slide along the receiver during movement of the bolt. This rearward position of the bolt defines a loading position, as the front end 36a of the bolt 32 is situated just behind the opening 44 12 through which metal balls are fed into the barrel by the magazine. With the trigger 28 and the stop member 100 biased into their default positions by the respective coil springs 90, 108, as shown in Figure 5, the top end of the stop member 100 projects into the recess 110 in the underside of the bolt 32, and the catch 106 at the bottom of the stop member catches under the forwardmost end of the slide member 92 exposed at the front of the trigger extension 86. The top end of the stop member abuts against the end of the bolt recess 110 nearest the larger diameter rear end 34a of the bolt, thereby blocking pivotal movement of the stop member 100 on the cross-pin 104 in the direction that would pull the catch 106 forwardly out from under the slide member 92 of the trigger extension 86. The raised position of the stop member 100 to engage into the recess 110 in the exterior of the bolt prevents any forward movement of the bolt 32. The forcing of the bolt 32 into its rearward position by the respective spring 40 causes the rear end 34a of the bolt 32 to push reward on the plunger 58, which in turn is long enough to push rearward on the closure sleeve 78 of the inlet valve against the spring 82 pushing forward thereagainst. The bolt spring 40 is stronger than the valve spring 82, and so this biasing of the bolt into the rearward loading position overcomes the bias of the valve spring 82 to move the valve closure sleeve 76 into the open position allowing airflow into the dump chamber.
With the HPA tank 30 connected, high pressure thus air flows into the dump chamber 20 through the inlet valve 66 contained inside the dump chamber, which may be regulated in a known manner to fill to a predetermined pressure. Once the pressure inside the dump chamber 20 reaches the predetermined value, the device is ready to fire the metal ball that has been automatically loaded into the barrel in front of the bolt by the magazine. When the trigger 28 is pulled rearward from the ready to fire condition of Figure 5, the catch 106 of the stop member 100 is pulled downward by the slide member 92 of the trigger extension 86 under the pivoting of the trigger and extension about the respective pin 84, thereby withdrawing the top end of the stop member 100 from the recess 110 of the bolt and thus unlocking the bolt from its rearward loading position, as shown in Figure 6. Initially the bolt is held in this rearward loading position by the respective spring 40. However, the high pressure air in the dump tank acts on the rear end of the plunger 58, pushing the plunger 58 forward in the dump tank. To cause this desired directional movement of the plunger 58, the rear end 58a of the plunger has a reduced diameter smaller than both the rear stop 60 located adjacent that end, and the intermediate portion of the plunger between the two stops 60, 62. This way, there is a greater surface area for the dump tank pressure to act against in the forward direction at the rear face of the rear stop 60 than in the rearward direction at the front face of the rear stop. The extension of this reduced-diameter rear end of the plunger past the rear stop creates a space in which the dump chamber air pressure can act between the plungers rear stop 60 and the closed end 78 of the inlet valve sleeve 76.
The inlet valve sleeve 76 follows the plunger 58 under the action of the respective spring 82, so that under sufficient forward travel of the plunger 58, the sleeve moves into the closed position turning off the inlet valve 66, thereby cutting off the supply of high pressure air to the dump chamber from the HPA tank 30.
The forward motion of the plunger 68 also pushes the bolt 32 forward in the receiver 18, so that simultaneous to, or just after, this shutting off of the inlet valve, the rear end of the bolt reaches the ports 54 in the receiver's peripheral wall, opening the ports as the seal near the rear end of the bolt moves past the rearmost extent of the ports.
This opening of these ports or vent holes in the receiver wall allows the HPA
contained in the dump chamber to rapidly expand through these vent holes, into the receiver, forcing the bolt to the fully forward position, and flowing through the axial bore in the middle of the bolt into the barrel, pushing the ball-shaped projectile out of the barrel at the muzzle. When in its rearward loading position, the front end of the bolt resides immediately behind the location where the magazine opens to the barrel, and so the initial movement of the bolt under the action of the plunger immediately begins to close off the magazine opening to the barrel above, and so the subsequent movement of the bolt under the introduction of the high pressure air to the receiver quickly completes this closure of the magazine in an effectively instantaneous manner to close of the magazine before any high pressure air can gain entry thereto. Circumferential seals (not shown) on the interior wall of the barrel on opposite sides of the magazine opening provide an air tight fit between the bolt and the barrel.
As described above, the stop member is spring loaded for two types of biased motion, a rotational motion and an upward sliding motion. Once it has been pulled downward by the trigger far enough to release the bolt, as shown in Figure 6, the stop member will rotate (clockwise in Figs. 3 & 4, counterclockwise in Figs.
2, 5 & 6) and disengage its catch 106 from under the slide member 92 of the trigger extension 86, as shown in Figure 7. Once it has disconnected from the trigger assembly, the stop member will be forced upward against the bolt, awaiting return of the bolt to its rearward position under the action of the bolt spring 40, where the stop member will then again align with the recess 110 in the underside of the bolt and lock into place in this recess to once again secure the bolt in the loading position, as shown in figure 8. The disconnecting of the stop member catch from the trigger makes the air gun operate in only a semi automatic mode of fire, as the trigger can remain depressed rearward after firing, and the stop member will nonetheless still stop the bolt from proceeding forward, as demonstrated in Figures 5-8. Once the trigger has been released, it will reconnect with the catch of the stop member, allowing for the device to be shot again with another depression of the trigger.
With reference to Figures 5 and 8, should the trigger only be released from the depressed condition of Figure 8 after the stop member 100 has returned to it's ready to fire position of engaged against the rear end of the bolt notch 110 as shown in Figure 5, the slide member 92 of the trigger will retract further into the trigger extension under contact of the slide with the stop member, which is clamped in place between the rear end of the bolt notch 110 and the front end of the barrel notch 102, while the front end of the trigger extension is raised under the return action of spring 90, thereby preventing the trigger extension from catching on the underside of the stop member 100. To ensure this a smooth trouble-free return of the trigger to its normal position, the front end of the slide 92 and the rear-bottom end of the stop member catch 106 are obliquely angled with a same forward and downward direction of slope so that under upward movement of the slide 92 with the trigger extension about pin 84, the slide's sloped forward end will slidingly interface with the sloped rear-bottom corner of the stop member catch 106, forcing the slide 92 back into the trigger extension 86 against spring 94 so as to clear the stop member catch 106 to allow return of the trigger to its normal default position. Once the slide has cleared the stop member catch 106, spring 94 returns the slide to its defaulted extended position, as defined by abutment of the rear end of slot 98 against pin 96 to once extend the front end of the slide 92 far enough forward to engage over the stop member catch 106.
Once the pressure inside the device has lowered, the spring loaded bolt starts travelling rearward, allowing another projectile from the magazine to load into the barrel, re-sealing the receiver from the dump chamber by closing the vent holes or ports of the receiver, and restarting the flow of HPA into the dump chamber from the HPA tank by pushing the plunger 58, and in turn the valve sleeve 76, rearward against the valve spring 82 to reopen the inlet valve 66. When the bolt has moved all the way rearward, the stop member 100 will lock the bolt 32 in its rearward position.
Once the dump chamber is again pressurized to the predetermined level, the device is ready to be fired again.
Performance To obtain a suitable balance between desired high-level muzzle energy and low enough muzzle velocity to avoid classification as a firearm under current Canadian legislation, one embodiment employs a 4500 psi HPA tank, a regulated dump chamber pressure of 2000 psi, an internal barrel diameter and a projectile diameter of approximately 1-inch, a 0.75-inch bore through the bolt.
Commercially available Portable HPA tanks come in many different capacities, including a range from 13 cubic inches to 110 cubic inches, and many different pressures, including a range from 3000 to 5000 PSI. The selection of PSI for the aforementioned embodiment is based on limited availability and high cost of higher pressure 5000 PSI tanks. The capacity of the tank could be any of the available sizes, for example depending on the preference of the end user.
Alternatively, specialized tanks of shape, size or dimension varying from existing commercially available units may of course be used.
A 68 cubic inch tank at 4500 PSI for example contains -20750 cubic inches of air at normal atmospheric pressure. For the example of a 1 inch diameter projectile, with a 6 inch barrel, a calculated average pressure needs to be -1500 PSI, to reach 421 fps with a muzzle energy of 589 foot pounds. For the embodiment employing the values listed above, the starting pressure would be 2000 PSI at the breech of the barrel, and 1000 Psi at the muzzle of the barrel, giving a 1500 PSI average down the length of the barrel. A tank of this pressure would need to be regulated for different models of the air gun or Personal Protection Device, to achieve consistent muzzle velocities independent of barrel diameter or length. That is, for shorter barreled models, the pressure contained within the dump chamber would need to be higher to achieve the same velocity as a longer barreled model with a lower pressure.
Based on the initial calculations, a tank size of 68 cubic inches 4500 PSI
would get approximately 26 full power shots out of a model built to the specifications listed as the first example in the table below.
Diameter Barrel Projectile Velocity Muzzle Energy (inch) Av PSI g. Length Weight (kg) (fps) (foot lbs) (inch) 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.75 1135 6 0.041 422.472 250.7138 0.75 1360 5 0.041 422.1617 250.3457 0.75 1700 4 0.041 422.1617 250.3457 0.75 2275 3 0.041 422.937 251.2661 0.5 750 6 0.0121 421.4428 73.63108 0.5 900 5 0.0121 421.4428 73.63108 0.5 1125 4 0.0121 421.4428 73.63108 0.5 1500 3 0.0121 421.4428 73.63108 The calculations used the projectile/barrel diameter, associated projectile weight for a preselected projectile material (e.g. lead), barrel length, and average barrel pressure as input values, from which the muzzle velocity and energy could be calculated. For the different projectile sizes and barrel lengths, calculations were repeated for various pressure values to find pressures suitable to achieve a muzzle velocity approaching, but less than, 500 feet per second. Selecting an approximate muzzle velocity of 420 feet per second as a desirable target, leaving a margin of 80 feet per second, led to the optimal values charted herein above. The charted calculation results of pressures required for different diameters and lengths of barrels demonstrate a preference for a 1-inch projectile based on the expected stopping power based on the calculated muzzle energy.
The 0.5" lead sphere at 421 FPS provides 73.6 ft/lbs of energy, while a 1.5"
lead sphere at 421 FPS provides 1992 ft/lbs of energy. Preferred embodiments would provide at least 662 ft/lbs of energy/square inch of the projectiles largest cross-sectional area (in planes normal to the barrel axis) and greater. The 1"
lead sphere with 589 ft/lbs of energy is equal to 755 ft/lbs per square inch, and should penetrate 14.25 inches of ballistic gelatin. This is just better than the 12.5-14 inches of penetration recommended by defensive experts. The 0.75" inner barrel diameter model with 250ft/lbs of energy, equal to 568ft/lbs per square inch, should penetrate 10.72 inches of ballistic gelatin. The .5" ID model with 73.6 foot pounds equal to 375 ft/lbs per square inch should penetrate 7.09 inches of ballistics gel.
Based on the above achievable energy values, 0.5" is the preferred minimum projectile size. Preferred embodiments would not exceed a projectile diameter of 1.5" to avoid excessive weight issues. Six 1.5" diameter lead spheres will still weigh 1.968 KG, with the larger device's weight on top of that. Six 1.75" diameter lead spheres would weigh 3.126 KG, six 2" lead spheres would weigh 4.668 KG.
Estimations suggest that the embodiment with the 6" long barrel with 1"
internal diameter barrel, fully loaded, would be almost 6 pounds. If the 1.5" internal diameter device would be 25% heavier, with the six 1,5" lead spheres it would be just over 10 pounds. If the 2" internal diameter device would be 50% heavier with six 2"
lead spheres, it would weigh almost 17.25 pounds.
It will be appreciated that aspects of the air gun design disclosed herein can also be employed to provide results other than the under 500-fps performance described above, for example in producing an air gun design that doesn't qualify as an exemption to the firearm definition reference in the background.
Accordingly, a wide variety of supply pressures, dump chamber pressures, projectile sizes and shapes may be used while still employing unique aspects of the design falling within the scope of the present invention. For example, versions lacking semi-automatic capabilities or magazine-carried projectiles may nonetheless employ the unique arrangement of a plunger used to initiate the firing process by displacing the bolt to open communication ports between the receiver and a pressurized dump chamber.
While the preferred embodiment features solid spherical projectiles fired one at a time to provide relatively stable short-distance flight without a rifled barrel, it may be possible to use shot, in combination with a wad or shot cup, or non-spherical single projectiles such as slugs of more elongated shape, for example of slug shape similar to pellets for a pellet rifle, with a heavy front end and skirted rear end, like a badminton birdie. However, the spherical projectiles of the illustrated embodiment avoid the issues of tumbling, barrel rifling and spin.
Some of the advantageous features of the air gun disclosed herein include:
- Semi-automatic repeater, firing one projectile for each pull of the trigger, and automatically reloading + resetting itself to be ready for the next pull of the trigger.
- Replaceable magazine.
- Able to be operated by one hand. 21 - multi-functional use of the bolt, including acting as a high speed valve for introducing the HPA to the receiver from the dump chamber via the receiver ports uncovered by initial displacement of the bolt.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
With reference to Figures 5 and 8, should the trigger only be released from the depressed condition of Figure 8 after the stop member 100 has returned to it's ready to fire position of engaged against the rear end of the bolt notch 110 as shown in Figure 5, the slide member 92 of the trigger will retract further into the trigger extension under contact of the slide with the stop member, which is clamped in place between the rear end of the bolt notch 110 and the front end of the barrel notch 102, while the front end of the trigger extension is raised under the return action of spring 90, thereby preventing the trigger extension from catching on the underside of the stop member 100. To ensure this a smooth trouble-free return of the trigger to its normal position, the front end of the slide 92 and the rear-bottom end of the stop member catch 106 are obliquely angled with a same forward and downward direction of slope so that under upward movement of the slide 92 with the trigger extension about pin 84, the slide's sloped forward end will slidingly interface with the sloped rear-bottom corner of the stop member catch 106, forcing the slide 92 back into the trigger extension 86 against spring 94 so as to clear the stop member catch 106 to allow return of the trigger to its normal default position. Once the slide has cleared the stop member catch 106, spring 94 returns the slide to its defaulted extended position, as defined by abutment of the rear end of slot 98 against pin 96 to once extend the front end of the slide 92 far enough forward to engage over the stop member catch 106.
Once the pressure inside the device has lowered, the spring loaded bolt starts travelling rearward, allowing another projectile from the magazine to load into the barrel, re-sealing the receiver from the dump chamber by closing the vent holes or ports of the receiver, and restarting the flow of HPA into the dump chamber from the HPA tank by pushing the plunger 58, and in turn the valve sleeve 76, rearward against the valve spring 82 to reopen the inlet valve 66. When the bolt has moved all the way rearward, the stop member 100 will lock the bolt 32 in its rearward position.
Once the dump chamber is again pressurized to the predetermined level, the device is ready to be fired again.
Performance To obtain a suitable balance between desired high-level muzzle energy and low enough muzzle velocity to avoid classification as a firearm under current Canadian legislation, one embodiment employs a 4500 psi HPA tank, a regulated dump chamber pressure of 2000 psi, an internal barrel diameter and a projectile diameter of approximately 1-inch, a 0.75-inch bore through the bolt.
Commercially available Portable HPA tanks come in many different capacities, including a range from 13 cubic inches to 110 cubic inches, and many different pressures, including a range from 3000 to 5000 PSI. The selection of PSI for the aforementioned embodiment is based on limited availability and high cost of higher pressure 5000 PSI tanks. The capacity of the tank could be any of the available sizes, for example depending on the preference of the end user.
Alternatively, specialized tanks of shape, size or dimension varying from existing commercially available units may of course be used.
A 68 cubic inch tank at 4500 PSI for example contains -20750 cubic inches of air at normal atmospheric pressure. For the example of a 1 inch diameter projectile, with a 6 inch barrel, a calculated average pressure needs to be -1500 PSI, to reach 421 fps with a muzzle energy of 589 foot pounds. For the embodiment employing the values listed above, the starting pressure would be 2000 PSI at the breech of the barrel, and 1000 Psi at the muzzle of the barrel, giving a 1500 PSI average down the length of the barrel. A tank of this pressure would need to be regulated for different models of the air gun or Personal Protection Device, to achieve consistent muzzle velocities independent of barrel diameter or length. That is, for shorter barreled models, the pressure contained within the dump chamber would need to be higher to achieve the same velocity as a longer barreled model with a lower pressure.
Based on the initial calculations, a tank size of 68 cubic inches 4500 PSI
would get approximately 26 full power shots out of a model built to the specifications listed as the first example in the table below.
Diameter Barrel Projectile Velocity Muzzle Energy (inch) Av PSI g. Length Weight (kg) (fps) (foot lbs) (inch) 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.097 421.0081 589.0486 0.75 1135 6 0.041 422.472 250.7138 0.75 1360 5 0.041 422.1617 250.3457 0.75 1700 4 0.041 422.1617 250.3457 0.75 2275 3 0.041 422.937 251.2661 0.5 750 6 0.0121 421.4428 73.63108 0.5 900 5 0.0121 421.4428 73.63108 0.5 1125 4 0.0121 421.4428 73.63108 0.5 1500 3 0.0121 421.4428 73.63108 The calculations used the projectile/barrel diameter, associated projectile weight for a preselected projectile material (e.g. lead), barrel length, and average barrel pressure as input values, from which the muzzle velocity and energy could be calculated. For the different projectile sizes and barrel lengths, calculations were repeated for various pressure values to find pressures suitable to achieve a muzzle velocity approaching, but less than, 500 feet per second. Selecting an approximate muzzle velocity of 420 feet per second as a desirable target, leaving a margin of 80 feet per second, led to the optimal values charted herein above. The charted calculation results of pressures required for different diameters and lengths of barrels demonstrate a preference for a 1-inch projectile based on the expected stopping power based on the calculated muzzle energy.
The 0.5" lead sphere at 421 FPS provides 73.6 ft/lbs of energy, while a 1.5"
lead sphere at 421 FPS provides 1992 ft/lbs of energy. Preferred embodiments would provide at least 662 ft/lbs of energy/square inch of the projectiles largest cross-sectional area (in planes normal to the barrel axis) and greater. The 1"
lead sphere with 589 ft/lbs of energy is equal to 755 ft/lbs per square inch, and should penetrate 14.25 inches of ballistic gelatin. This is just better than the 12.5-14 inches of penetration recommended by defensive experts. The 0.75" inner barrel diameter model with 250ft/lbs of energy, equal to 568ft/lbs per square inch, should penetrate 10.72 inches of ballistic gelatin. The .5" ID model with 73.6 foot pounds equal to 375 ft/lbs per square inch should penetrate 7.09 inches of ballistics gel.
Based on the above achievable energy values, 0.5" is the preferred minimum projectile size. Preferred embodiments would not exceed a projectile diameter of 1.5" to avoid excessive weight issues. Six 1.5" diameter lead spheres will still weigh 1.968 KG, with the larger device's weight on top of that. Six 1.75" diameter lead spheres would weigh 3.126 KG, six 2" lead spheres would weigh 4.668 KG.
Estimations suggest that the embodiment with the 6" long barrel with 1"
internal diameter barrel, fully loaded, would be almost 6 pounds. If the 1.5" internal diameter device would be 25% heavier, with the six 1,5" lead spheres it would be just over 10 pounds. If the 2" internal diameter device would be 50% heavier with six 2"
lead spheres, it would weigh almost 17.25 pounds.
It will be appreciated that aspects of the air gun design disclosed herein can also be employed to provide results other than the under 500-fps performance described above, for example in producing an air gun design that doesn't qualify as an exemption to the firearm definition reference in the background.
Accordingly, a wide variety of supply pressures, dump chamber pressures, projectile sizes and shapes may be used while still employing unique aspects of the design falling within the scope of the present invention. For example, versions lacking semi-automatic capabilities or magazine-carried projectiles may nonetheless employ the unique arrangement of a plunger used to initiate the firing process by displacing the bolt to open communication ports between the receiver and a pressurized dump chamber.
While the preferred embodiment features solid spherical projectiles fired one at a time to provide relatively stable short-distance flight without a rifled barrel, it may be possible to use shot, in combination with a wad or shot cup, or non-spherical single projectiles such as slugs of more elongated shape, for example of slug shape similar to pellets for a pellet rifle, with a heavy front end and skirted rear end, like a badminton birdie. However, the spherical projectiles of the illustrated embodiment avoid the issues of tumbling, barrel rifling and spin.
Some of the advantageous features of the air gun disclosed herein include:
- Semi-automatic repeater, firing one projectile for each pull of the trigger, and automatically reloading + resetting itself to be ready for the next pull of the trigger.
- Replaceable magazine.
- Able to be operated by one hand. 21 - multi-functional use of the bolt, including acting as a high speed valve for introducing the HPA to the receiver from the dump chamber via the receiver ports uncovered by initial displacement of the bolt.
Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.
Claims (25)
1. A pneumatically powered projectile launcher comprising:
a barrel having a breech end and a muzzle end;
a receiver disposed at the breech end of the barrel and having ports located proximate a closed rear wall of the receiver at an end thereof opposite the barrel;
a dump chamber containing a rear portion of the receiver, including the closed rear wall and the ports of the receiver;
a hollow bolt slidably movable in the receiver between a loading position, in which the bolt resides adjacent the closed rear end of the receiver to close off the ports, and a launch position, in which the bolt is spaced further from the closed rear end of the receiver to extend further into the barrel;
an inlet valve in fluid communication with the dump chamber and arranged for connection to a pressurized gas supply;
a plunger extending through the rear end of the receiver with a rear end of the plunger in the dump chamber and a front end of the plunger in the receiver, the plunger being slidable back an forth in the rear end of the receiver and being arranged to slide further into the receiver under pressurization of the dump chamber to push on the bolt, when in the loading position, in a direction toward the barrel; and a trigger mechanism comprising a trigger movable between a normal position, in which the trigger mechanism engages the bolt when in the loading position to retain the bolt in said loading position, and a depressed position in which the trigger mechanism is released from engagement with the bolt;
whereby with the bolt in the loading position and retained therein by the trigger mechanism, pressurization of the dump chamber by the gas supply pushes the plunger against the bolt and subsequent depressing of the trigger releases the bolt for displacement thereof past the ports of the receiver to communicate the pressurized gas from the dump chamber into the receiver to act against and through the bolt to force a projectile in the barrel through the muzzle end thereof.
a barrel having a breech end and a muzzle end;
a receiver disposed at the breech end of the barrel and having ports located proximate a closed rear wall of the receiver at an end thereof opposite the barrel;
a dump chamber containing a rear portion of the receiver, including the closed rear wall and the ports of the receiver;
a hollow bolt slidably movable in the receiver between a loading position, in which the bolt resides adjacent the closed rear end of the receiver to close off the ports, and a launch position, in which the bolt is spaced further from the closed rear end of the receiver to extend further into the barrel;
an inlet valve in fluid communication with the dump chamber and arranged for connection to a pressurized gas supply;
a plunger extending through the rear end of the receiver with a rear end of the plunger in the dump chamber and a front end of the plunger in the receiver, the plunger being slidable back an forth in the rear end of the receiver and being arranged to slide further into the receiver under pressurization of the dump chamber to push on the bolt, when in the loading position, in a direction toward the barrel; and a trigger mechanism comprising a trigger movable between a normal position, in which the trigger mechanism engages the bolt when in the loading position to retain the bolt in said loading position, and a depressed position in which the trigger mechanism is released from engagement with the bolt;
whereby with the bolt in the loading position and retained therein by the trigger mechanism, pressurization of the dump chamber by the gas supply pushes the plunger against the bolt and subsequent depressing of the trigger releases the bolt for displacement thereof past the ports of the receiver to communicate the pressurized gas from the dump chamber into the receiver to act against and through the bolt to force a projectile in the barrel through the muzzle end thereof.
2. The projectile launcher of claim 1 comprising a bolt biasing mechanism biasing the bolt into the loading position.
3. The projectile launcher of claim 1 or 2 wherein the inlet valve is arranged to automatically close during movement of the bolt from the loading position to the firing position.
4. The projectile launcher of claim 2 comprising a valve biasing mechanism arranged to bias the inlet valve into a closed condition, wherein the .
plunger is arranged to oppose and overcome the valve biasing mechanism to open the inlet valve under movement of the bolt into the loading position by the bolt biasing mechanism.
plunger is arranged to oppose and overcome the valve biasing mechanism to open the inlet valve under movement of the bolt into the loading position by the bolt biasing mechanism.
5. The projectile launcher of claim 4 wherein the bolt biasing mechanism comprises a first spring forcing the bolt toward the loading position and the valve biasing mechanism comprises a second spring forcing a closure member of the valve into a closed position, the first spring providing a first action on the bolt of opposite direction and greater strength than a second action provided on the valve closure member by the second spring.
6. The projectile launcher of any one of claims 1 to 5 in combination with a magazine of projectiles engageable to the projectile launcher adjacent the breach end of the barrel and arranged to load a projectile into the barrel adjacent the breech end thereof at a position ahead of the bolt when in the loading position.
7. The projectile launcher of claim 6 wherein the projectiles are round ball projectiles.
8. The projectile launcher of claim 6 or 7 wherein the projectiles are metal.
9. The projectile launcher of any one of claims 1 to 8 wherein the trigger mechanism comprises a bolt stop member movable into and out of a stopping position blocking movement of the bolt from the loading position, and is arranged to return the bolt stop member to the stopping position, after each withdrawal therefrom by a respective depression of the trigger, regardless of whether the trigger is subsequently released.
10. The projectile launcher of any one of claims 1 to 9 in combination with the pressurized gas supply, wherein the pressurized gas supply has a pressure between 3000 psi and 5000 psi, inclusive.
11. The projectile launcher of claim 10 wherein the pressure of the pressurized gas supply is approximately 4500 psi.
12. The projectile launcher of any one of claims 1 to 11 wherein the barrel has an inner diameter between 0.5-inch and 1.5-inch, inclusive.
13. The projectile launcher of any one of claims 1 to 12 in combination with at least one projectile of predetermined size for launching from the barrel, the predetermined size being between 0.5-inch and 1.5-inch in diameter, inclusive.
14. The projectile of claim 13 wherein the predetermined size is 0.75-inch or greater.
15. The projectile of claim 13 wherein the predetermined size is 1-inch or greater.
16. The projectile launcher of any one of claims 1 to 15 wherein the gas from the pressurized gas supply is regulated to pressurize the dump chamber to a pressure having a predetermined value between 500 and 4500 psi.
17. The projectile launcher of claim 16 wherein the predetermined value is approximately 2000 psi.
18. The projectile launcher of any one of claims 1 to 17 arranged in combination with a projectile to launch said projectile from the barrel with an output muzzle velocity less than 500 feet per second and an output muzzle energy greater than 4.2 foot pounds.
19. A pneumatically powered projectile launcher comprising a manually trigger-activated semi-automatic launching mechanism and arranged to launch a projectile from a barrel of the projectile launcher with a muzzle velocity less than 500 feet per second and an output muzzle energy greater than 4.2 foot pounds.
20. A pneumatically powered projectile launcher having a muzzle velocity less than 500 feet per second and an output muzzle energy greater than 250 foot pounds.
21. The projectile launcher of claim 20 having an output muzzle energy greater than 500 foot pounds.
22. A pneumatically powered projectile launcher arranged to launch a projectile from a barrel of the projectile launcher with having a muzzle velocity less than 500 feet per second and an output muzzle energy having a value equal to or greater than 500 foot pounds per square inch of a largest cross-sectional area of the projectile in a plane normal to an axis of the barrel.
23. The projectile launcher of claim 22 wherein the muzzle energy value is equal to or greater than 600 foot pounds per square inch of the largest cross-sectional area of the projectile.
24. The projectile launcher of claim 22 wherein the muzzle energy value is equal to or greater than 700 foot pounds per square inch of the largest cross-sectional area of the projectile.
25. The projectile launcher of any one of claims 19 to 25 having an inner barrel diameter of 0.75-inch or greater.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2756606 CA2756606A1 (en) | 2011-11-01 | 2011-11-01 | Pneumatically powered projectile launcher or air gun |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2756606 CA2756606A1 (en) | 2011-11-01 | 2011-11-01 | Pneumatically powered projectile launcher or air gun |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2756606A1 true CA2756606A1 (en) | 2013-05-01 |
Family
ID=48464182
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2756606 Abandoned CA2756606A1 (en) | 2011-11-01 | 2011-11-01 | Pneumatically powered projectile launcher or air gun |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2756606A1 (en) |
-
2011
- 2011-11-01 CA CA 2756606 patent/CA2756606A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |
Effective date: 20151103 |