US20160363406A1

US20160363406A1 - Integrated Barrel Assembly for Firearm

Info

Publication number: US20160363406A1
Application number: US14/738,103
Authority: US
Inventors: Justin Wiesblott; Anthony Arria
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-06-12
Filing date: 2015-06-12
Publication date: 2016-12-15

Abstract

An integrated barrel assembly, configured to cooperate with a firearm receiver assembly firearm, comprises a barrel having a breech end and a muzzle end and a connector for securing and aligning it with the receiver assembly. The design eliminates the need for a separate barrel and barrel extension and improves the structural integrity and performance of the firearm. The barrel defines a bolt head cavity, a chamber, and a bore all in fluid communication and serially extending from its breech end to muzzle end, and an internal breech face is created where the bolt head cavity meets the chamber. The bolt head cavity comprises bolt-locking lugs and angled feed ramps, and the chamber and bore are configured to cooperate with a particular cartridge case and projectile. The barrel preferably comprises steel or a steel alloy and a coating applied to the barrel's outer surface, inner surface, ends, and gas port.

Description

FIELD OF THE INVENTION

The present invention relates to firearms and, more particularly, to an integrated barrel assembly for use with a firearm.

BACKGROUND OF THE INVENTION

In general, firearms comprise at least a receiver assembly and a barrel assembly. The receiver assembly includes all of the moving parts that load, fire, and eject the firearms shells or cartridges. The barrel assembly attaches to and cooperates with the receiver assembly and includes the long metal tube with a bore that provides the exit path for the discharging projectile. Once the projectile is fired, due to expanding gas forces, it travels down the barrel from its initial position at the breech end of the barrel through an opening in the barrel's muzzle. In order for the firearm to operate properly and to achieve a high level of accuracy, the specifications of the barrel must correspond to the type and size of bullet being fired. For example, the bore of the barrel corresponds to the caliber of bullet being fired, and the chamber near the breech end of the barrel corresponds to the headspace and configuration of the projectile's cartridge case.
The typical barrel assembly for many types of firearms, including for semiautomatic rifles in particular, attaches to the receiver, or the upper receiver if the firearm has an upper and a lower receiver, with a barrel extension. The barrel extension includes a chamber for receiving a cartridge, lugs for interlocking with a rotatable bolt disposed in the receiver, angled feed ramps for loading cartridges into the chamber, a pin for indexing the barrel and barrel extension properly in the receiver, an outer flange for securing the barrel extension to the receiver, and a threaded inner surface that cooperates with external threads on the breech end of the barrel. The cooperating barrel includes a bore, which is often rifled, and the external threads that cooperate with the internal threads of the barrel extension. Additionally, the barrel may include a small opening or gas port. Together, the barrel and barrel extension comprise the main barrel assembly, and the two components must be fitted together precisely to optimize the firearm's performance. The barrel assembly is often secured to the receiver with a barrel nut that cooperates with the flange on the barrel extension. Barrel assemblies have traditionally included both a barrel and barrel extension for at least two reasons: so that the user can change barrels as needed and to facilitate manufacturing processes.
The firearm barrel can be removed and replaced for several types of firearms, such as bolt-action, semiautomatic and automatic pistols, sub machine guns, and rifles. Barrels may be removed and replaced for several reasons including to repair a worn barrel, to improve the characteristics of the firearm itself, or to change the performance of the firearm. Additionally, in some cases, the field conditions or combat environment may dictate what type of barrel should be used. For example, in close-quarters engagement, shorter and lighter barrel assemblies may be preferred. Alternatively, when firing at greater distances, a longer and heavier barrel may be desired to improve accuracy. Removing the barrel from the barrel assembly and replacing it with a new or different barrel, however, is complicated. When attaching a new or different barrel, it must be precisely fit to the barrel extension such that the gas port is properly aligned, the mated threads are aligned, and the proper amount of torque is applied. If not done properly, a misfit barrel can lead to cracking, fractures, or other structural failures of the entire barrel assembly.
One of the issues primarily associated with changing a barrel is that of insuring that proper headspace or chamber clearance distance between the shoulder in the cartridge chamber of the barrel and the bolt block face when the latter is in firing position. Headspace is one of the most critical measures of a firearm and is essential to accuracy, reliable functioning, and cartridge case life. Headspace is the distance measured from the region of the chamber that stops forward motion of the cartridge, referred to as the (datum reference) to the face of the bolt. Simply defined, it is the space between the head of the cartridge case and the breech. This is often referred to as chamber clearance. This space limits the forward movement of the cartridge as it is impacted by the firing pin.
When a barrel is threaded into a barrel extension one must gauge the axial position of the barrel in order to insure proper head space before the barrel is locked into position. A failure to provide adequate head space can result in jamming of the firearm due to the cartridge not properly sliding into the chamber opening in a direct axially aligned longitudinal position with the barrel. Conversely, providing too much headspace can result in lite primer strikes resulting in misfires and additional wear on parts due to the additional forces needed to chamber the cartridges. Too much headspace can cause the cartridge to rupture on firing, without the proper chamber seating around the cartridge body and neck, perhaps damaging the firearm and possible injuring the shooter. Accordingly, it would be desirable to provide an integrated barrel assembly that allows for easy removal and replacement when the barrel assembly becomes worn or when the user desires a barrel assembly with different features.
Firearm barrel assemblies include both a barrel and a barrel extension because of the traditional manufacturing process and are expected to be assembled by experienced and qualified gun manufacturers with the proper tools to ensure the precise tolerances are met. Typically, the barrel is machined independently from the extension. Then, both the barrel and barrel extension separately receive a coating if desired. After being coated or treated, then the barrel extension gets threaded on to the barrel and torqued to a broad range of approximately 50-150 lbs. Once torqued, a gas port is drilled though the barrel, and the indexing pin is press fit into an opening on the outer wall of the barrel extension. The gas port must be aligned with the indexing pin, so that when the firearm is assembled, the gas port, pin, and cooperating upper receiver gas tube hole are all aligned for proper function.
Unfortunately, the traditional manufacturing process of making a separate barrel extension and barrel itself leads to several problems. First, the barrel and barrel extension may have different levels of hardness or temper. Second, the threads may become stripped or cross-threaded when the two components are mated. Third, the connection between the mated components may loosen with time and use, requiring retightening or possibly also adding an adhesive, which can further compromise the components structure, hardness, or strength. Fourth, over-tightening of the components can lead to eventual cracks or fractures. Fifth, the precise measurements for optimizing the firearms functioning, chambering, internal pressure management, and accuracy, are not easily achieved when threading the barrel and barrel extension together. Sixth, because the gas port is created after the coating process, it becomes vulnerable to corrosion and build-up as the raw exposed metal of the port itself is subjected to hot, high pressure, cartridge discharge gas residues. Seventh, because the components are coated or treated prior to being assembled together, the coating or treatment can alter the threads on the barrel and barrel extension and compromise their threaded engagement. Due to these additional disadvantages of the two component barrel assembly system, it would be further desirable to provide an integrated or single-component barrel assembly.

SUMMARY OF THE INVENTION

The integrated barrel assembly of the present invention is particularly useful for firearms that ordinarily require a barrel extension such as some bolt action, semiautomatic and automatic pistols, sub machine guns, rifles and, in particular, firearms with upper receiver assemblies and especially those converted for accurate feeding and firing of cartridges. The integrated barrel assembly is configured to cooperate with a receiver assembly of a firearm and comprises a barrel having a breech end and a muzzle end. The barrel defines a bolt head cavity at its breech end, a chamber in fluid communication with the bolt head cavity, and a bore in fluid communication with the chamber that extends to the muzzle end of the barrel. The bolt head cavity, chamber, and bore together comprise a barrel cavity that extends from the breech end of the barrel to its muzzle end. The bolt head cavity meets the chamber at an internal breech face. The bolt head cavity comprises a cavity configured to cooperate with the bolt head of the cooperating receiver assembly, bolt-locking lugs, and angled feed ramps for loading and/or expelling cartridges to and from the adjacent chamber. The bolt-locking lugs are configured to cooperate with and engage bolt lugs formed on the forward end of the rotatable and axially reciprocating steel bolt assembly slide mounted in the cooperating receiver assembly and optimally provides a steel-to-steel interlock designed that resists the forces of combustion when the firearm is fired, in both the battery and recoil positions. The entire barrel preferably is constructed from a single piece of steel or steel alloy. After the bolt head cavity, chamber, and bore are machined, and after the gas port is drilled through the barrel wall, a protective coating can be applied to the entire barrel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a barrel extension of the prior art.

FIG. 2 is a side view of a barrel extension of the prior art.

FIG. 3 is a partial perspective view of a barrel assembly of the prior art.

FIG. 4 is a perspective view of the barrel assembly of the present invention.

FIG. 5 is a side view of the barrel assembly of the present invention.

FIG. 6 is an end view of the breech end of the barrel assembly of the present invention.

FIG. 7 is a cutaway top view of the barrel assembly of the present invention as cut along the line —VII-VII— of FIG. 5.

FIG. 8 is a magnified cutaway side view of the breach end of the barrel assembly of the present invention.

FIG. 9 is a top view of the barrel assembly of the present invention.

FIG. 10 is a cutaway side view of the barrel assembly of the present invention as cut along the line —X-X— of FIG. 9.

FIG. 11 is an illustration of a cartridge case and its descriptive nomenclature.

FIG. 12 is an illustration of various types of cartridge rim styles.

FIG. 13 is an illustration of various cartridge case rim styles and the defined headspace datum measurement regions.

FIG. 14 is an illustration of several parts of a cartridge.

FIG. 15 is an illustration of a typical 7.62 mm/0.308 chamber and internal descriptive nomenclature.

FIG. 16 is an illustration of the appropriate bullet position relative to proper seating of the cartridge case headspace chambering relative to the barrel rifling.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The embodiments disclosed herein are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and they mean at least one. Additionally, where the shapes, relative positions and other aspects of the parts described in the embodiments are not clearly defined, the scope of the embodiments is not limited only to the parts shown, which are meant merely for the purpose of illustration. Also, while numerous details are set forth, it is understood that some embodiments may be practiced without these details. In other instances, well-known structures and techniques have not been shown in detail so as not to obscure the understanding of this description.
FIGS. 1-3 illustrate the prior art two-component barrel assembly, and FIGS. 4-10 illustrate the integrated barrel assembly of the present invention. As shown in FIGS. 1-3, the conventional two-component barrel assembly has a barrel 10 and a removable barrel extension 12. In order for the barrel assembly of the prior art to operate properly, the barrel 10 and barrel extension 12 must be connected together with cooperating threads. In particular, the two components must be mated precisely to ensure proper headspace for the cartridge containing the projectile to be fired. Moreover, the barrel 10 and barrel extension 12 must be connected using the proper torque to ensure a properly aligned and secure connection that is unlikely to fracture or crack. If the barrel extension 12 is out of tolerance due to incorrect tightness, not only is the barrel extension wall likely to fracture due to over tightening resulting in failure under pressure, but also the feed ramps will not be aligned properly or may become misaligned due to a loose connection, so that the bullet meplat 302 (nose or point of the bullet as shown in FIG. 14) does not accurately engage the sloped feed ramps resulting is a miss-aligned bullet which is no longer moving in a longitudinally axial insertion datum alignment with the internal bore of the barrel. This affects not only the functional reliability of the firearm, but can have a demonstrable effect on both the internal and external ballistics of the projectiles performance
The integrated barrel assembly of the present invention eliminates the problems associated with the two component design and is particularly useful for firearms such as bolt action, semiautomatic and automatic pistols, sub machine guns, rifles and, in particular, firearms with upper receiver assemblies and especially those converted for accurate feeding and firing of cartridges. The integrated barrel assembly is configured to cooperate with a receiver assembly of a firearm and, as shown in FIGS. 4-10, comprises a barrel 100 and a connector or alignment structure such as a preferred but optional indexing pin 101. Barrel 100 has a breech end 102 that cooperates with the receiver assembly of the firearm and a muzzle end 104 where the fired projectile exits. Barrel 100 defines a bolt head cavity 110 at its breech end 102, a chamber 112 in fluid communication with the bolt head cavity 110, and a bore 114 in fluid communication with the chamber 112. Bore 114 extends from the chamber 112 to the muzzle end 104 of the barrel. Together, the bolt head cavity 110, chamber 112, and bore 114 comprise a barrel cavity that extends from the barrel's breech end to muzzle end.
Barrel 100 comprises an outer surface 100 a and an inner surface 100 b, where the barrel material disposed between the outer surface 100 a and inner surface 100 b comprises the barrel wall 100 c and where the inner surface 100 b generally forms the outer walls of barrel cavity, including the outer wall of the bore 114, chamber 112, and bolt head cavity 110. Barrel 100 additionally defines a gas port 116 disposed through the barrel wall 100 c such that it extends from the outer surface 100 a to the inner surface 100 b and is in fluid communication with bore 114. Gas port 116 is configured to cooperate receiver assembly gas tube and is preferably positioned in a gas block landing region 164 of barrel 100.
The bolt head cavity 110 defined by barrel 100 comprises internal bolt-locking lugs 130 with angled feed ramps 132 for loading cartridges (not shown) into the chamber 112. The bolt-locking lugs 130 are configured to cooperate with and engage bolt lugs formed on the forward end of a rotatable and axially reciprocating steel bolt assembly slide mounted in the cooperating receiver assembly (not shown). Receiver assemblies including rotatable and axially reciprocating steel bolts are well-known in the art and conventional bolts generally include bolt lugs intended for cooperating with barrel assemblies. The angled feed ramps 132 are configured to cooperate with the type and size of cartridges intended for use with the barrel 100, as is well-known in the art. The bolt head cavity 110 preferably is sized to accommodate the cooperating bolt of the receiver assembly such that the bolt can extend into the bolt head cavity, interlock with the lugs 130, and cooperate with a loaded cartridge.
The chamber 112 abuts the bolt head cavity 110 at the internal breech face 118. Internal breech face 118 is created because the chamber 112 comprises a smaller diameter than the bolt head cavity 110. Chamber 112 is preferably configured to accommodate a specific cartridge case and includes several sections that cooperate with the specific cartridge case and its respective headspace. For example, FIG. 15 illustrates a chamber 112 for a typical 7.62 mm/0.308 chamber cartridge having a headspace 143. As shown, chamber 112 comprises a body section 140 having a substantially constant first body diameter, a neck 144 having a substantially constant first neck diameter, and a first shoulder 142 between the body section 140 and neck 144 and having a tapered diameter from a larger first body diameter to the smaller first neck diameter. Chamber 112 further comprises a freebore area 148 having a first freebore diameter, and a second shoulder 146, where the second shoulder is positioned between neck 144 and freebore area 148 and has a tapered diameter from the larger first neck diameter to the smaller freebore diameter. Finally, as shown, chamber 112 includes a throat 150 having a first throat diameter where throat 150 cooperates with bore 114. FIG. 15 further illustrates how the chamber sections are in fluid communication with each other and with bolt head cavity 110 and bore 114. FIG. 16 illustrates a projectile is properly positioned within the chamber 112 and bore 114. While FIGS. 15 and 16 illustrate specific examples of cartridges, projectiles, and chamber sections, a variety of chamber sections can be used according to the present invention. Additionally, the diameters of the sections can be constant, tapered, or otherwise configured without altering the scope of the present invention. The chamber sections and relative dimensions should be configured to cooperate with the type of projectile, size of projectile, and specifications of the cartridge case. FIG. 11 illustrates an example cartridge case 200 having a case head 202, body 204, shoulder 206, neck 208, extractor groove 210, and rim 212. The headspace 214 of case 200 extends from the rim 212 to partway along shoulder 206. FIG. 12 illustrates several types of cartridges as well: rimmed cartridge 220, rimless cartridge 222, semi rimmed cartridge 224, belted cartridge 226, and rebated cartridge 228. FIG. 13 illustrates the various headspaces (shown with arrows) for different cartridge cases. FIG. 14 illustrates the parts of a typical projectile (nose or meplat 302, head or ogive 304, shoulder 306, cannelure 308, bearing surface 310, boat tail 312, heel 314, and base 316).
Bore 114 comprises a substantially continuous diameter and is preferably substantially centered along the longitudinal axis of barrel 100. Bore 114 can include grooves 152 (shown in FIGS. 15 and 16) or rifling intended to induce spin on the projectile to improve accuracy.
Barrel 100 preferably also defines an indexing pin receptacle 120 disposed in the outer wall 100 a of barrel 100. The indexing pin is configured to cooperate with the indexing pin 101 such that the indexing pin 101 can be press fit into receptacle 120. Preferably, receptacle 120 is somewhat tapered from a larger diameter at the outer surface 100 a of barrel 100 to a smaller diameter within the barrel wall 100 c. Receptacle 120 does not extend all the way through wall 100 c, however. Index pin receptacle 120 is preferably aligned with gas port 116 along the outer circumference of the barrel such that when the index pin receptacle 120 and cooperating index pin 102 are positioned at the top of the barrel as shown in FIG. 10, the gas port 120 is also positioned at the top of the barrel as shown in FIG. 10.
A flange 160 optionally surrounds barrel 100 near its breech end such that it extends axially outward from the barrel 100. Preferably, flange 160 is continuous so that it extends around the circumference of the barrel as shown in the Figures. Flange 160 is also preferably configured to cooperate with an optional barrel nut (not shown) or other fastener that facilitates attaching the barrel 100 to a cooperating receiver assembly. Alternatively, other connectors or connecting structures can be substituted for flange 160 to facilitate connecting the barrel to the receiver assembly, such as lugs, clamps, or threads.
Along with or instead of flange 160 or indexing pin 101, other connectors or alignment structures can be substituted to facilitate connecting, aligning, or both connecting and aligning the barrel 100 to a receiver assembly. Other connectors or alignment structures include any structure that can align or orient a component such as grooves, ridges, indentations, and protrusions. Additionally, connectors can include all types of fasteners and fastening components such as flanges, grooves, pins, locks, lugs, screws, clamps, and adhesives.
Barrel 100 may further comprise external threads 170 or other connectors at its muzzle end to accommodate optional accessories such as silencers or suppressors. Barrel 100 may optionally also include a milled undercut area 180 surrounding the circumference of barrel 100 near or adjacent to flange 160 to facilitate mating barrel 100 to the upper receiver assembly of the firearm. Barrel 100 may also have an uneven outer surface or a tapered outer surface to accommodate accessories, to decrease weight, and for other reasons known to someone skilled in the art.
Preferably, the barrel is comprised of steel or a steel alloy. Any material can be used, however, provided it resists the high temperatures and extremely high internal chamber pressures that occur when the firearm is discharged. Steel blank material can be, for example, grade 4140 steel, grade 4145 steel, grade 4150 steel, or grade 416 stainless steel. Alternatively, the present invention can be manufactured using alloy modified steel and titanium variants or hybrids capable of being designed specifically to handle the high heat and pressure requirements. New firearm platforms are constantly under design to reduce weight, so qualified metallic alloy hybrids for other embodiments on the horizon may also be suitable.
With respect to 4140, 4145, and 4150 types of steel that are useful for the present invention, they are medium carbon steel alloys, or Chrome-Molybdenum steel alloys commonly referred to as chrome-moly or Cro-Moly. Chrome-Moly is relatively inexpensive and readily available, is easily machined, can be hardened by heat treatment, and is easily blacked. Medium-carbon steels are similar to low-carbon steels except that the carbon ranges from 0.30 to 0.60% and the manganese from 0.60 to 1.65%. Increasing the carbon content to approximately 0.5% with an accompanying increase in manganese allows medium carbon steels to be used in the quenched and tempered condition. The American Iron and Steel Institute (AISI) 4140 alloy steel is chromium, molybdenum, manganese containing low alloy steel. It has high fatigue strength, abrasion and impact resistance, toughness, and torsional strength. AISI 4150 alloy steel is a higher carbon variation of chromium, manganese, molybdenum 4100 low alloy steel.
With respect to low-alloy steels useful for the present invention, they constitute a category of ferrous materials that exhibit mechanical properties superior to plain carbon steels as the result of additions of alloying elements such as nickel, chromium, and molybdenum. Total alloy content can range from 2.07% up to levels just below that of stainless steels, which contain a minimum of 10% Cr. For many low-alloy steels, the primary function of the alloying elements is to achieve certain properties in the material such as increase hardenability in order to optimize mechanical properties and toughness after heat treatment. As a guideline, alloying elements are added in lower percentages (less than 5%) to increase strength or hardenability, or in larger percentages (over 5%) to achieve special properties, such as corrosion resistance or extreme temperature stability. As with steels in general, low-alloy steels can be classified according to their chemical composition, such as nickel steels, nickel-chromium steels, molybdenum steels, chromium-molybdenum steels, and according to their heat treatment, such as quenched and tempered, normalized and tempered, annealed. Due to the wide variety of chemical compositions possible, and the fact that some steels are used in more than one heat-treated condition, some overlap exists among the alloy steel classifications.
With respect to 416 and other types of stainless steel that are useful for the present invention, they are generally a martensitic steel that shares some characteristics with ferritic stainless steel, but boasts higher levels of carbon, up to a full 1%. These types of stainless steel can be tempered and hardened and are thus highly useful in situations where the strength of the steel is more important than its resistance to corrosion. It is more accurately a high chrome content (>10%) steel having enough sulphur to give it good machining properties. This steel is generally used by target shooters and is considered to be easier to machine accurately than chrome-moly steels. It is also more expensive than chrome-moly steel, has lesser life and is more difficult to black. Hence, military and hunting rifles use chrome-moly steel while target shooters prefer stainless steel.
Other considerations when selecting a material for manufacturing the barrel assembly of the present invention, is that the material have a high tensile strength. The preferred steel and steel alloys can easily withstand over 100,000 psi which is a bit over the maximum expected pressure (caliber defined) which have from 65,000 psi nominal SAAMI pressure requirement to as much as 96,500 psi for the maximum peak tested SAAMI performance capability. Hardening steels generally increases tensile strength, but it tends to make them brittle and susceptible to intense external impacts, hence these steels must withstand shock as well. A tradeoff is made between tensile strength and impact strength and therefore, the barrels typically are hardened.
Other considerations when selecting material for the barrel assembly may be considered as well. For example, barrel-quality stainless steel, usually identified as type 416R or 416RS, is preferred over warehouse-grade 416 as it has approximately half the sulfur content of warehouse-grade 416. Stainless steel barrels will not harden in the throat area, which provides a big advantage for target shooters who plan to set their barrels back when the throat region has increased wear. The erosion pattern of stainless steel looks similar to a dried-up mud puddle, having large flats with fracture lines. This reduces the drag on the bullet, so there is a reduced tendency for vertical stringing at long ranges. Although infrequent, and subsequent to substantial amounts of firing, a portion may dislodge out from the throat of a stainless steel barrel, causing it to lose accuracy. Stainless steel will also scratch or peen easier than chrome-moly barrel steel of comparable hardness. In applications involving military weapons, this sort of material behavior would be problematic, which is why chrome-moly is generally used. Stainless steel also has less ductility than chrome-moly, particularly when the ambient temperature approaches zero. Stainless steel is easier to machine than chrome-moly.
After machining the barrel assembly from a blank, preferably a coating is applied to the entire barrel assembly including the gas port. Applying the coating after the barrel assembly has been machined, and especially after the gas port has been drilled through the barrel wall, allows for a complete and uniform, external and internal coating that precludes surface wear, corrosion, and heat damage. Additionally, it aids in fatigue and rolling fatigue strengths of moving parts. Any type of coating can be applied as desired including ones that enhance the performance of or the appearance of the integrated barrel assembly. Preferably, a coating for this application is one applied in a molten salt bath (ferritic nitrocarburizing), such as Melonite®, a registered trademark of Kolene Corporation, where nitrogen, carbon, and small amounts of oxygen are diffused into the surface of the steel, creating an epsilon iron nitride layer (e-FexN). The active constituent in the bath is the alkali cyanate. The Nitrocarburizing process step is conducted at approximately 896-1,166° F./480-630° C., the standard temperature is approximately 1,076° F./580° C. These three elements bind and produce a single layer that impregnates the steel much deeper than traditional gun bluing or chroming which only covers the surface layer. Once cured it induces a hardness to the surface of approximately a Rockwell 55-65. The process nominally only adds 0.0005-inches (five ten-thousandths of an inch) of dimension to the treated metals which in turn does not require any additional grinding to remove as it's within the design specs of the firearm, as the top the layer of the process is exposed to oxygen, its turns a natural uniform dark black color. There are three other classes of Ferritic Nitrocarburizing: gaseous, ion or plasma, and fluidized-bed. These processes are most commonly used on low-carbon, low-alloy steels, medium and high-carbon steels, and stainless steels. The advantage of this process over many other coating, hardening and finishing processes in the industry which can be considered viable process to other embodiments, is that you can achieve complete uniform coverage throughout the entire barrel, internal threading, and gas port openings.
The present invention cooperates with the receiver assembly of a firearm to receive a cartridge and fire the projectile. The sequencing of the loading of the rifle cartridge into a position in the chamber ready for firing must go through a sequence of steps without any interferences or internal receiver mechanical part failures (stoppages and/or malfunctions) to perform this function whether in a single shot, semiautomatic, or full automatic mode of operation. The present invention minimizes such interferences and failures. As the cartridge is drawn from the magazine follower by the forward motion of the bolt carrier assembly, it is pressed into a longitudinally axial insertion datum alignment with the internal bore of the barrel breech face. Then, when the firing pin of a firearm strikes the primer of a cartridge, the primer compound ignites sending a flame into the cartridge case. Gunpowder in the cartridge case starts to burn (deflagration), causing it to change from a solid material to a gas. This internal thermo-chemical combustion process reaction change creates pressure within the cartridge, which in turn forces the bullet down the barrel and down range. Pressure developing behind the bullet is released when the bullet exits the muzzle of the firearm. The spent cartridge is also then extracted from the chamber and ejected through an ejection port, and the bolt and bolt carrier assembly return to their initial positions.
The cartridge discharge residues in combination with the high heat and internal pressures create a proportional amount of firearm internal mechanical malfunctions. Incorrect dimensional support around the cartridge case, would be catastrophic. Additionally, stoppages and malfunctions can be the result of too much part movement, inadequate dimensional stability between all of the internal action groups, such as the bolt carrier assembly, and the direct steel-to-steel breech interlock designed to resist the forces of combustion when the firearm is fired, in both the battery and recoil positions.
The integrated barrel assembly of the present invention addresses the many undesirable issues that arose from having a separate barrel and barrel assembly. The present invention provides a single component barrel-to-bolt assembly lug interlock which merely requires the axial insertion and rotation of the barrel into the upper receiver/action of the firearm to insure proper locking of the barrel, thereby creating an immediate proper head space, barrel index pin and gas tube alignment, and appropriate tightening torque of the barrel nut.
A first attribute of this invention is obtaining an inter-engaging of the barrel lugs and the bolt lugs in an axial insertion and rotation to insure proper locking of the bolt lugs to a fixed depth where the headspace is automatically fixed in a singular barrel replacement. Various cartridge and caliber designs require varied headspace dimensional constraints. Some of the cartridge case base designs are: rimless, semi-rimmed, rimmed, belted, and rebated, as shown in FIG. 12. Headspace is one of the most critical measures of a firearm, and is essential to accuracy, reliable functioning, and cartridge case life. Example headspace areas are shown in FIG. 13. For a rimless cartridge headspace is the distance from the bolt face to the point in the chamber that is halfway up the shoulder of the cartridge case. There is no general perfect optimum headspace gap for firearm accuracy, as it can be minute with little to no tolerance, or large with as much as 0.01025″ in tolerance, in some limited instances. Headspace determines the specific distance from the face of the bolt locked into a datum line or shoulder in the chamber that arrests the forward movement of the cartridge. The term “headspace” originated when all cartridges had protruding rims, so the distance was initially only taken from the head of the cartridge. As cartridges changed for rifles, and automatic machine guns, not to mention handguns, so too has the measured distance from the various cartridge designs. With a one piece barrel with an integral internal breech and a bolt head cavity, you gain overall reliability, rigidity, durability, and mechanical strength to increase overall functional and accuracy performance.
A second attribute of the present invention is eliminating a threaded barrel extension screwed onto a barrel. Having a barrel with an integral internal breech with a bolt head cavity which contains internal bolt-locking lugs with angled feed ramps for loading cartridges into the chamber which is formed between this breech end of the barrel and the muzzle, eliminates an additional machined part (barrel extension), that is screwed onto the barrel. This ensures that a consistent hardening of the single barrel assembly, rather than two individual components with varying hardness or temper. This also precludes stripping of the threads during installation, tightening for adjustment, or just cross threading the extension during installation. It is common for the barrel extension to loosen up and require re-tightening, oftentimes with the addition of an adhesive similar to Locktite®, a registered trademark of Henkel Corporation, that provides the adhesion strength and high heat resistance. The undesirable outcome with the use of an adhesive, is the subsequent removal attempt once the barrel is worn out, or there is a failure issue with the barrel extension. The previously applied adhesive precludes easy removal oftentimes requiring heating up the extension to burn out the adhesive, or requiring the use of a vise or other steel clamping method that in itself can damage either the barrel or the barrel extension. Heating up the barrel extension also has a direct change on the hardness and temper of the barrel extension steel, so that it no longer has its original designed hardness and strength. Additionally, overtightening of the barrel extension is common, with instances where the outer wall of the barrel extension has been cracked, or a fracture initiated but not seen until the heat from multiple firings expands the fractured area and forces a complete brittle fracture resulting in the failure under the added high gas pressures exerted upon it. The industry has torque specifications for tightening the barrel extension varying from as little as 50 to as much as 150 foot pounds. A 100 foot pound variance is not even considered close to any limited tolerance specification.
A third attribute of this invention is that the gas port for semi-automatic and automatic rifles will always maintain a precise alignment longitudinally to the bore as it is machined from a single material stock blank. Utilizing a barrel extension requires that it is screwed onto the barrel by way of the external barrel threads and the internal barrel extension threads, and there is always a specific amount of free play between both components as a matter of functionality for installation by thread design. Eliminating free play eliminates the need to check the headspace through the utilization of a single unit. The threads do not precisely align for the optimum fit with a removable barrel extension, which often requires excessive overtightening to align the gas port tube, in an attempt to preclude loosening from firing over a period of time. Firing a firearm requires that the parts of the action endure substantial amounts of pressures, impact abuse, stresses, corrosion, torque, and compression. Parts that are too tight fail without allowed tolerance for high temperature and pressure expansion, and parts which are too loose fail from impact abuse, unequal or support resistive stresses, and torque.
A fourth attribute of this invention is the exact concentricity of the integral combination which is extremely precise, as the entire unit in manufactured from a single material stock blank. Thousandths of an inch in adjustments or spacing are imperative to optimized firearm functioning, chambering, internal pressure management, and accuracy, between multiple part components, and utilizing a single material stock black precludes the necessity to focus on such adjustments every time a barrel is changed out, or other bolt carrier components are interchanged.
A fifth attribute of this invention is the decrease in assembly time to manufacture and assemble in addition to the increase in profitability for the manufacturer, and/or lowered cost to the end user. Additionally, the reduction in human involvement is reduced eliminating a portion of the quality assurance and quality control necessary to ensure specification tolerances, as computer numerical control (CNC) machinery is employed in the manufacture of a single stock black fabrication.
A sixth attribute of this invention is the emergency field replacement of a barrel for a military semi-automatic or automatic firearm eliminating multiple processes to change out multiple components, which ultimately will not ensure precise and accurate headspace dimensions and/or alignment.
A seventh attribute in one embodiment of this invention is that the entire barrel assembly including the gas port can achieve complete and uniform, external and internal coating to preclude surface wear, corrosion, and heat damage. Additionally, it aids in fatigue and rolling fatigue strengths of moving parts. The advantage of this process over many other coating, hardening and finishing processes in the industry which can be considered viable process to other embodiments, is that you can achieve complete uniform coverage throughout the entire barrel and gas port where previously the coating was not able to coat the gas port and created problems when applied to the cooperating threads of prior art barrels and barrel extensions.
An eight attribute of this invention is the functionality of mass produced barrels which are interchangeable without any restrictions within the caliber, chamber, head space, and action configuration.
A ninth attribute of this invention is the ability to ensure proper feeding of commercial, military and precision ammunition cartridge components.
While there has been illustrated and described what is at present considered to be the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the true scope of the invention disclosed, but that the invention will include all embodiments falling within the scope of the claims.

Claims

We claim:

1. An integrated barrel assembly for cooperating with a receiver assembly of a firearm comprising:

a. a barrel comprising a muzzle end, a breech end, an inner surface, an outer surface, and a barrel wall, wherein the barrel inner surfaces defines a barrel cavity extending from its breech end to its barrel end and wherein the barrel wall is disposed between the barrel inner surface and the barrel outer surface; and

b. a connector configured to cooperate with the receiver assembly of the firearm such that the barrel assembly can be directly aligned with or attached to the receiver assembly without a barrel extension;

c. wherein the barrel cavity defined by the barrel inner surface comprises:

i. a bolt head cavity in fluid communication with the breech end of the barrel and configured to cooperate with a bolt of the firearm receiver assembly;

ii. a chamber in fluid communication with the bolt head cavity and configured to cooperate with a cartridge case and projectile; and

iii. a bore in fluid communication with the chamber and the muzzle end of the barrel and configured to direct a projectile out of the muzzle end of the barrel after the projectile has been fired.

2. The integrated barrel assembly of claim 1 wherein the connector comprises an indexing pin, wherein the barrel assembly comprises a pin receptacle disposed in the barrel out surface and defined by the barrel wall; and wherein the index pin is secured in the pin receptacle with a press fit.

3. The integrated barrel assembly of claim 1 wherein the bolt head cavity comprises one or more lugs defined by the barrel and disposed at its circumference at the breech end of the barrel wherein the legs are configured to cooperate with lugs on the bolt of the receiver assembly;

4. The integrated barrel assembly of claim 3 wherein the bolt head cavity further comprises one or more feed ramps defined by the barrel and disposed at its circumference at the breech end of the barrel.

5. The integrated barrel assembly of claim 1 wherein the general diameter of the chamber is smaller in size than the general diameter of the bolt head cavity, and wherein an inner breech surface is disposed in the barrel cavity at the transition between the bolt head cavity and the chamber.

6. The integrated barrel assembly of claim 1 further comprising a gas port defined by the barrel wall, extending from the barrel outer surface to the barrel inner surface, and positioned to be in fluid communication with the bore.

7. The integrated barrel assembly of claim 2 further comprising a gas port defined by the barrel wall, extending from the barrel outer surface to the barrel inner surface, and positioned to be in fluid communication and such that it is substantially aligned with the indexing pin so that when the indexing pin is positioned at a first circumferential position on the barrel, the gas port is likewise positioned at a first circumferential position on the barrel.

8. The integrated barrel assembly of claim 1 wherein the barrel comprises a rigid material capable of resisting high temperatures and high pressure exerted in the barrel cavity.

9. The integrated barrel assembly of claim 8 wherein the barrel further comprises a coating substantially evenly disposed over the outer barrel surface and the inner barrel surface.

10. The integrated barrel assembly of claim 7 wherein the barrel comprises a rigid material capable of resisting high temperatures and high pressure exerted in the barrel cavity and a coating substantially evenly disposed over the outer barrel surface, the inner barrel surface, and the surface of the gas port.

11. An integrated barrel assembly for cooperating with a receiver assembly of a firearm consisting of:

b. a connector configured to cooperate with the receiver assembly of the firearm such that the barrel assembly can be directly attached to or aligned with the receiver assembly without a barrel extension;

c. wherein the barrel cavity defined by the barrel inner surface comprises:

12. The integrated barrel assembly of claim 1 wherein the connector comprises an indexing pin, wherein the barrel assembly comprises a pin receptacle disposed in the barrel out surface and defined by the barrel wall; and wherein the index pin is secured in the pin receptacle with a press fit.

13. The integrated barrel assembly of claim 1 wherein the bolt head cavity comprises one or more lugs defined by the barrel and disposed at its circumference at the breech end of the barrel wherein the legs are configured to cooperate with lugs on the bolt of the receiver assembly;

14. The integrated barrel assembly of claim 3 wherein the bolt head cavity further comprises one or more feed ramps defined by the barrel and disposed at its circumference at the breech end of the barrel.

15. The integrated barrel assembly of claim 1 wherein the general diameter of the chamber is smaller in size than the general diameter of the bolt head cavity, and wherein an inner breech surface is disposed in the barrel cavity at the transition between the bolt head cavity and the chamber.

16. The integrated barrel assembly of claim 1 further comprising a gas port defined by the barrel wall, extending from the barrel outer surface to the barrel inner surface, and positioned to be in fluid communication with the bore.

17. The integrated barrel assembly of claim 2 further comprising a gas port defined by the barrel wall, extending from the barrel outer surface to the barrel inner surface, and positioned to be in fluid communication and such that it is substantially aligned with the indexing pin so that when the indexing pin is positioned at a first circumferential position on the barrel, the gas port is likewise positioned at a first circumferential position on the barrel.

18. The integrated barrel assembly of claim 1 wherein the barrel comprises a rigid material capable of resisting high temperatures and high pressure exerted in the barrel cavity and a coating substantially evenly disposed over the outer barrel surface and the inner barrel surface.

19. The integrated barrel assembly of claim 7 wherein the barrel comprises a rigid material capable of resisting high temperatures and high pressure exerted in the barrel cavity and a coating substantially evenly disposed over the outer barrel surface, the inner barrel surface, and the surface of the gas port.

20. An integrated barrel assembly for cooperating with a receiver assembly of a firearm comprising:

a. a barrel, formed from a single piece of rigid material capable of withstanding high temperature and high pressure, comprising:

i. a muzzle end and a breech end;

ii. an inner surface, an outer surface; and a barrel wall; wherein the barrel inner surface defines a barrel cavity extending from its breech end to its barrel end and wherein the barrel wall is disposed between the barrel inner surface and the barrel outer surface;

iii. a pin receptacle defined by the barrel wall and disposed on the barrel outer surface;

iv. a flange integral with the barrel wall and disposed around the outer surface of the barrel;

v. a gas port defined by the barrel wall, extending from the barrel outer surface to the barrel inner surface, and positioned to be in fluid communication with the barrel cavity and positioned such that it is substantially aligned with the pin receptacle so that when the pin receptacle is positioned at a first circumferential position on the barrel, the gas port is likewise positioned at a first circumferential position on the barrel; and

vi. a coating substantially evenly disposed over the outer barrel surface, the inner barrel surface, and the surface of the gas port; and

b. an indexing pin secured in the pin receptacle with a press fit and configured to cooperate with the receiver assembly of the firearm such that the indexing pin and flange facilitate attaching the barrel assembly to and aligning the barrel assembly with the receiver assembly without a barrel extension;

c. wherein the barrel cavity defined by the barrel inner surface comprises:

i. a bolt head cavity in fluid communication with the breech end of the barrel and configured to cooperate with a bolt of the firearm receiver assembly; wherein the bolt head cavity comprises one or more lugs integral with the barrel wall and disposed at the bolt head cavity circumference at the breech end of the barrel wherein the legs are configured to cooperate with lugs on the bolt of the receiver assembly and wherein the bolt head cavity further comprises one or more feed ramps defined by the barrel and disposed at its circumference at the breech end of the barrel;

ii. a chamber in fluid communication with the bolt head cavity comprising two or more chamber sections of varying diameters, wherein the chamber sections are configured to with a cartridge case and projectile; and

iii. a bore in fluid communication with the chamber and the muzzle end of the barrel and configured to direct a projectile out of the muzzle end of the barrel after the projectile has been fired; where in the bore comprises one or more grooves formed along the barrel inner surface.