US2489747A - Reduced recoil type gun - Google Patents

Description

Nov. 29, 1949 c. D. BURNEY REDUCED RECOIL TYPE GUN 6 She'etS-Sheei, l

Filed Sept. l, 1944 c. D. BURNEY 2,489,747

REDUCED REcoIL TYPE GUN Nov. 29, l949 Filed Sept. 1, 1944 6 Sheets-Sheet 2 Il mentor A Home Nov. 29, 1949 c. n. BURNEY 2,489,747

REDUCED REcoIL TYPE GUN Filed Sept. l. 1944 6 Sheets-Sheet 3 s F/G. e.

lnuenlor Bw/Adn A Home)` Nov. 29, 1949 I c. D. BURNEY 2,48S,747 V REDUCED REOIL TYPE GUN Filed Sept. 1, 1944 6 Sheets-Sheet 4 [Zivil ttorney Nov. 29., 1949 c. D. BURNEY REDUCED RECOIL TYPE GUN Filed Sept. 1, 1944 6 Sheets-Sheet 5 Attorney Nov. 29, 1949 c. D. BuRNl-:Y

REDUCED macon TYPE Gun 6 Sheets-Sheet 6 Filed Sept. l. 1944 Miara@ I n 1re/1101 M M Lb Patented Nov. 29, 1949 2,489,747 REDUCED RECOIL TYPE GUN Charles Dennstoun Burney, Baynards Park,

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Cranleigh, England Application September 1, 1944, Serial No. 552,347 In Great Britain December 5, 1941 Section 1, Public Law .690, August 8, 1946 Patent expires December 5, 1961 7 Claims.

The present invention relates to ordnance and small arms, and has for its object to eliminate the recoil of the gun on ring, thereby enabling the firearm to be the shoulder, using heavy projectiles, without discomfort or injury to the rer, or enabling artillery or naval guns to be fired from very light mountings and with a minimum of stress upon the deck or hull.

Attempts have already been made to reduce the recoil of guns by rearward discharge Yof the chamber gases to produce a forward reaction acting against the rearward kick of the barrel, with varying degrees of success. For example, it has been proposed to provide, at the muzzle end of the gun, deflector surfaces for the gases muzzle, which reverse the direction of motion of the gases and cause a reaction which opposes recoil of the gun barrel. It has also been proposed in the case of trunnion mounted guns to allow the gases of combustion, after passing for a short distance down the barrel, to discharge through ward direction, thus producing a action opposing therecoil of the barrel. both of these arrangements, however, only a relatively small proportion of the recoil shock is absorbed. By means of the present invention, however, any proportion, up to 100 per cent of the recoil shock can be absorbed, according to requirements.

Also it has been proposed to provide expanding passages in the rear wall of the breech block adjacent to the base of the cartridge to permit rearward escape of the chamber gases on ring into an outwardly flared deflector for the purpose of reducing or eliminating the recoil of the gun.

Furthermore it has been proposed to construct a gun with an explosion chamber, an expansion nozzle between the said chamber and the gun barrel, a chamber or space behind the projectile into which said nozzle opens, and a passage or passages extending from said space to the outside of the gun, which is or are directed outwardly and rearwardly.

Guns according to the present invention are distinguished from the prior art in regard to the construction of the breech end of the gun, and according to one feature of the invention there is an extension in rear of the cartridge chamber, formed by a breech chamber which provides a space between the space occupied by the cartridge and one or more rearwardly directed gas nozzles or outlets at the rear end of the breech chamber.

issuing from the The invention includes guns having a cartridge chamber forming a co-axial rearward extension of the gun barrel, and co-aXially in rear of the cartridge chamber a free space communicating with the atmosphere through one or more rearwardly directed nozzles or gas outlets, and it also includes guns having a free space co-axially behind the projectile which communicates with the atmosphere through one or more rearwardly directed nozzles or outlets, and a cartridge chamber disposed laterally of the axis of the gun and communicating with said space.

In conformity with the foregoing, according to the invention, the improved gun may have a breech which includes a cartridge chamber or space, and a gas storage chamber or space which constitutes an enlargement or extension of the breech chamber and is open to the atmosphere through one or more rearwardly directed gas discharge nozzles, through which the gases discharge to the atmosphere.

Furthermore the cartridge chamber at the rear end of the gun may be closed by a movable breech block which contains a gas chamber adapted to form an extension or enlargement of the car' tridge chamber, said breech block having one or more rearwardly directed gas discharge nozzles or outlets communicating with said gas chamber.

From the foregoing it will be appreciated that a gun according to the invention is, in effect, an open ended tube, with the projectile and the propelling charge loaded into it at a medial point in its length. When iiXed ammunition is used, the cartridge case, instead of having a closed base with the firing cap in the centre thereof, has an open base, and is of rim re type. Provision may be made to cover the open base of the cartridge with some material which will make the cartridge water-tight, but will easily be shattered and consumed on ring, to avoid choking the nozzle.

The open ended tube or barrel is made up of two parts viz. a rearward extension or breech portion, and the front part or barrel proper, with the cartridge chamber. The rear or breech contains a gas chamber and is fitted with one or more rearwardly directed gas discharge nozzles, said breech part being movable in relation to the front part, to permit insertion of the projectile and cartridge into the front part, whereafter of the cartridge to grip the rim of the cartridge between the two barrel portions.

Instead of absorbing the whole recoil of the gun by gas reaction of the chamber gases, part the rear part is closed on the basel of the recoil may be absorbed by gas reaction and part by the gun mounting. In this connection the gun may be loaded with two charges, one of which is of quick burning type for propulsion of the projectile, and the other of a slow burning type, which remains active in retarding the recoil of the barrel after the projectile has left the gun muzzle.

It may be found desirable in the larger types of mounting by using a firing charge less than that necessary to balance the 'I in order to reduce the back blast of the recoil resisting gases to a reasonable extent. Further, in the case of small arms, even when the charge` required to absorb the whole of the recoil is small enough to produce a reasonable back blast, it may, a charge less than that required to absorb the whole recoil shock so as to retain a certain 'amount of barrel recoil, in order to operate mechanism, such as automatic reloading mecha'-v in the case of small arms of the automatic or'nrachine gun type.

It will be understood that the invention as described above involves the -use of a greatly augmented charge of propellant, i. e. a charge several times the maximum which could be safely used in a gun of given calibre vif operating with arclosed chamber, and the bulk of the gases developed by kcombustion of the propellant are discharged through the nozzles. Thus the car'- tridge chamber must be 'considerably larger than that of a standard gun of equal power in order to produce the same muzzle velocity whilst a1- lowing at least 50% or more of the gases produced to be discharged through the nozzles.

The exact proportion o'f the gases thus dis charged rearwardly will depend upon the'extent to which it is desired that the recoil be absorbed, and the proportion will depend upon the area of the nozzle lor the sum lof the nozzle areas, in felation to the bore area of the gun barrel.

For the complete elimination Vof the recoil 'it has' been found, for example, that in one type of gun the nozzle area should bev substantially 66% ofthe barrel cross-sectional area, in which case about six times the volume of gases is discharged through the nozzles than is Vdischarged through the barrel.

In most cases the gun will be designed to produce either complete recoil elimination 'or balance of a xed percentage of recoil, leaving the balance of recoil for the operation of automatic unloading and loading gear, or the like, as in automatic or machine guns. lEn some cases, however, it may be desire'd to vary the amount of recoil energy absorbed, and in these circum= stances means may be provided for blocking 'a proportion of the nozzles in. symmetrically disposed pairs, or in the case of a central nozzle For varying its effective area by means of a pointed valve member adjustably mounted in :he nozzle.

According to another feature of the present nvention, 'a grid o'r perforated screen may be lrovided between the chamber space to be oc upied by the propellant charge and the nozzles, o Serve the dual purpose of Ypreventing ejection f unconsumed propellant through the nozzles nd maintaining a free space' through which the ropellant gases may pass to the nozzle or nozzles.

Preferably the grid or screen` is in the form of cage-like member having slotted or perforated alls which change the direction of the gas ow gun to take up part of the recoil on the recoil SHOCK entirely,

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- the chamber but resist passage of any solid particles of propellant. The said member may, for example, be in the form of a truncated cone mounted in the breech portion of the gun, which carries the nozzles and contains the chamber in which the grid or screen member is mounted, with its narrow end towards the propellant when loaded in space at the rear end of the gun barrel proper.

- In carrying the invention into practice the gun chamber may comprise two sections, one of which receives Vthe `propellant and the other of which 4 from all directions.

nevertheless, be found desirable to use y contains a grid or equivalent member separating the'charge from the nozzles and forming a space permitting free access of the gases to the nozzles The rst section may confrom the barrel structure, to permit loading of the projectile andl propellant charge into the barrel and chamber respectively. The breech section may consist of a casing open at its front end and enclosing a chamber containing a grid or cage, which may be of truncated cone shape, with its narrow end: towards the barrel and its inclined walls perforated or saw out. The rear wall of the breech casi-ng is formed by a nozzle plate havlng one or more outwardly flared nozzles metrical ring of nozzles, or both.

Thev cartridge chamber proper or space cori--4 taining the propellant v' size to accommodate a number of nozzles havof the barrel it will be obirig 'a total throatarea equal to 66% bore area.v With this arrangement,

area ofthe barrel, so 'that the gases can escape not less freely through the gas space than along the barrel bore.

` For `reasons of stability, propelled projectiles are particularly when selfused, it may be necesanti-tank rifle according to the invention:

= Figure 1 is a longitudinal section of the front portion of the rifle,

Figure 2 is a longitudinal section of the rear portion,

Figure 3 is an end elevation with the breech closed and the gas discharge nozzle removed,

, Figure 4 is an end elevation with the breech open, part being broken away,

f Figure 5 is an end elevation with the breech chamber removed and partly in section,

Figure 6 is a detail view to a larger scale of the iiring mechanism, and

Figure '7 is a detail view of the extractor mechanism;

Figure 3 is a diagram showing a modified construction of recoilless gun in regard to the disposition of the cartridge chamber,

Figure 9 is detail view of the breech and firing mechanism of a 31/2 low velocity recoilless gun according to the invention, Figures 10, 11 and l2 are detail views of the extractor mechanism of Fig. 9, Figures 1l and 12 showing the positions of the parts with the breech closed and open respectively,

Figure 13 shows a 3.45", 25 pounder recoilless field gun in accordance with the invention,

Figure 14 is a detail view showing the breech block in the open position,

Figure 15 is a View of the breech block to a larger scale showing the locking mechanism and the extractor mechanism, and A Figure 16 is a detail view of one of the breech trunnions.

Figures l to '7 of the drawings illustrate a construction of 1.9" recoilless gun according to the invention, intended for use mainly as an antitank riiie and designed for use as a shoulder Weapon.

The barrel consists of a steel tube I which may have a smooth, but preferably has a ried bore. On the rear end of the barrel i is mounted the cartridge chamber 2, to which is connected the breech block or member containing chamber 3, which is rotatably supported in a cradle or frame 4 pivoted to the cartridge chamber 2 at 5. The rear end of the chamber 3 has an opening which is covered over within the chamber 3 by a perforated cage or grid 5 which supports in its interior an adjustable valve member 8 which can be screwed in or out to regulate the elective size of the gas discharge opening in the end of the chamber 3. The said opening is tted externally with a gas discharge nozzle or funnel I which prevents undue spread of the discharge gases.

VThe breech block 3 is adapted to be rotated in its cradle or carrier 4 by a handle 9, and it has an interrupted screw-thread engagement with the mouth of the cartridge chamber 2. The handle 9 is provided with a locking catch IG and when this is operated the breech block 3 can be rotated in the cradle 4 into a position in which the interrupted threads are disengaged, thus permitting the breech chamber to be opened by angular movement of the block 3 away from the cartridge chamber 2 into the position shown in Figure 4.

The forward part of the barrel carries a pistol grip II with which is associated a trigger I2, having a safety catch I2a, and pressure on the trigger pulls the wire I3 connected at the breech of the gun to the ring mechanism. A short distance in rear of the grip II is a curved shoulder rest I4, which is located at such a point 6 that the C.G. of the gun lies vertically above its resting point on the shoulder. This is an important feature of design in regard to rendering the gun easy to handle and control, which becomes a difcult matter in the case of a heavy gun if the bulk of the weight is forward of the shoulder. The location of the shoulder rest I4, therefore, has an important effect on the manoeuvrability of the gun.

The wire I3 passes along beneath the barrel and inside a metal cover plate I5, and at its breech end is attached to a pivoted lever I6.

The lever IB (see Figure 6) has a nose I'l adapted, when lever I5 is rocked by a pull on wire I3, to strike a pin I8 on a pivoted catch lever I9 having its tail pressed downwardly by a spring 20 and its nose 2| engaged with the head 22 of the ring rod 23, when the firing mechanism is cocked (as shown). The rod 23 carries a nut 24 and is surrounded in a casing I3a by a spring 25 bearing between a fixed shoulder and the nut 24. When the ring rod 23 is released by depression of the catch lever I9 by pivoted lever I6, the rod 23 es rearwards under the pressure of spring 25 and in so doing its head 22 strikes the end of the pivoted lever 26, the other end of which is engaged with the end of a ring pin 2'I whose nose 28 is located opposite to the percussion cap of the cartridge loaded into the chamber 2 of the gun. l

The rocking lever I6 also has another arm having a nose 29, which enters a recess or notch 30 in the breech block 3 when the lever rocks to release the ring pin 21, so that at the moment of firing the breech block 3 is positively locked against rotation in cradle 4, additionally to the lock provided by handle catch IIJ.

The firing rod 23 is automatically moved forwardly into its cocked position shown in Figure 2 by the opening of the breech into the position shown in Figure 4. This is accomplished by means of a U-shaped stirrup member 23h the arms of which are pivoted at 23a, to the breech end of the barrel structure, Whilst the rear end of said member 23h (Fig. 6) passes round the rear end of firing rod 23. When firing has taken place the rod 23 moves back into contact with the loop of stirrup member 23h and as the breech is opened is pulled forwardly in relation to the breech block until the nose 2l on lever I9 reengages behind the head 22 of rod 23. The ring rod 23 can be held against rearward movement by a pivoted safety catch 23e (Fig. 2).

The extractor mechanism is, for the sake of clearness, not shown in Figures 2 and 6, but is shown in Figure 4, and in detail in Figure 7. In a recess in the edge of the cartridge chamber, which comes beneath the rim of the cartridge case, is a part circular extractor fork 3l mounted on two short arms 36 pivoted about axis 32. The hub portions of said arms 36 have projecting noses 33, which are engaged by the ends of curved levers 34. The levers 34 rotate about axis 5 supported by lugs 35 on the cartridge chamber 2, and the breech carrier 4 also rotates about said axis 5, on which it is pivoted by means of arms 3l. On the outer sides oi the hub-portions of levers 34 are teeth 38, whilst on the inner sides of arms 31 are co-operating abutments, which when the breech is fully opened strike against teeth 33 and thus suddenly rotate said levers, so that their noses, by their engagement with the noses 33 on the extractor levers 3S, cause a sudden movement of the extractor 3| out of its recess,

whereby the cartridge case is forcibly dislodged from the cartridge chamber 2.

From the foregoing general descriptiono the invention it Will be appreciated that the propel l. 1-ing charge is ignited in chamber 2, and this is freely open to the atmosphere through the cham ber 3 and its discharge opening through grid 6 and funnel member 7. `As will be apparent from Figure 2, the gases developed by combustion of the charge in cartridge space 2 are free to expand jor vent into the space v3 through an opening which is somewhat larger in area than the forward end of the cartridge space and the rear end of the barrel. The grid 6 serves to prevent any 'of the propelling charge being blown out ofY chamber 3 in an unburnt condition, andY also nto main tain a clear space' over the'discharge opening of said chamber, allowing free access of the `gases Eto said opening.

:The extent to which the barrel recoil is elimilnated willdepend upon the relative areas of the discharge opening of chamber 3 and the barrel cross-sectional area, and this relation can be controlled by adjustment of valve 8 which can be adjusted by a tool, such as a turn screw', through funnel member 1. If the valve 8 is adjusted so that the effective area of the gas discharge opening is substantially 66% yof the barrel vcross-'section, then the barrel recoil will be substantially completely eliminated. In the present case since the valve t would be adjusted to give complete elimination of recoil, 1but if the gun were vadaptedto operate as a machine gun it would be `supported on a mounting and the valve 8 adjusted to allow suflicient barrel recoil to operate the necessary automatic loading and ring mechanism. By throttling down the gas ldiscl'large opening the `barrel recoil will be increased, but at the same time the chamber pressure operative on; the bullet will be increased, so that a higher muzzle velocity and greater range -or lpenetrating power of the bullet will result, whereby a` Vdegree of flexibility in the tactical power of the gun is obtainable if desired. In some cases, for `considerations of lstability of the projectile, the muzzle portion of the gun may be perforated in known manner for a short' length, so that the gases following the projectile may leak off to any desired extent before the projectile leaves the muzzle. By this meansy .the gas pressure on the base of the projectile may be gradually destroyed before it leaves the muzzle. This perforated lengthY of the barrel is preferably surrounded by a conica-l or tapering casing 98, open at its forward Vend surrounding 'the muzzle. By way of example the barrel perforations may befof a total area four times the area of the barrel bore, and the maximum area of the annu'- lar space between the gun muzzle and the conical casing may be twice the bore area. It will be found that the perforation of the' muzzle will produce a forward reaction on the. barrel tending to counteract the recoil, so that if this was fully balanced by making the nozzle' area 66% of the bore area the gun will, 'on firing,` tend to move forwardly in the same direction as the projectile. Consequently if muzzle perforation is adopted, the nozzle area should be reduced below 66% of the bore area to balance the recoil' completely without overbalancing it. On the ther hand if a cover 98 :is used over the perforazions this in itself will cause a considerable in-V :rease in the backward recoil so that it may become necessary to increase the nozzle area to a percentage exceeding the 66% of the borearea required for balancing 'the recoil of the barrel alone.

Figure B is a diagram. illustrating a modihed constructionof wherein the cartridge chamber 2 is not coaxial with the gun at the rear; end of the barrel, butis located .at the side of the barrel. The figure shows the cartridge case 33 with the projectile 40 Aafter it has travelled a 'short distance along the barrel from its vloaded position just in front ofthe grid member 6. With this construction the breech cover 4I covers the ends of both the cartridge chamber r2 andA the breech end of the barrel I, andY when the breech n'isv opened the cartridge case'BS and the projectile 40 are loaded side .by side into the gun. Y

In the case of the 1.9 gun illustrated by Figures 1 to 7. the cartridge case, which is generally of frustro-conical shape, has a relatively thiol; metal side wall but its ends are closed by thin walls, such as of metal foil, which are readily disrupted and/'or consumed When the charge is ignited. Such end walls may be held in position and reinforced by end members comprising ,peripheralrings witha number "of radial spiderarms meeting centrally within the ring. In the case; however, of the modification `illustrated by AFigure 8, it is necessary for the side Walls, insteadr of the ends of the cartri'dgecase, to be readily disruptible and/or consumable, for which reason *theV cartridge case has relatively thickI endl `walls and a cylindrical side wall oft-hin metal, or foil, reinforced and supported by spaced longitudfi'nalsupporting bars d2, as shown.

Figures 9 to lf2 illustrate aconstructionsuitable for a 3% 'low pressure gun for tiring fir-'project ing explosive bombs or like projectiles, and may be adapted for use as a shoulder fired weapon; or as a mortar.

In the 'case of a shoulder fired weapon vthe front-portion ofthe maybexsubstantially sim ilar 'to that of the 1.9 rifle of Figures, 1to '7; and the breecl'rportion. is-shown to a larger scale in Figure 9. In this case the breech block cham ber 50 swings in a plane transverse to the bore of the gun, about an axis parallel to the barrel axis but laterally displaced therefrom. .It is heldclosed position by a locking pin 43, engaged in a hole 4M ina lug 45 on the Wall fof cartridge chamsuitable mechanism not shown in detail in the drawing, a slide-43 into apositionlocking or blocking the ring pin 5l against movement, the slide llllrbeing provided with an opening through which the ring pin may pass when the breech block closed, 'but which is moved-out of register with the. ring `pin upon operation `of the catch d'6.

The firing pin '5| is connectedy to a. rocking lever, 52 pressed by a spring 53 ina direction to pull' the firing. pin bac The breech block 5E) is. mounted on a sleeve l54 rotatable in bearings ori lever 58.

The Vlever 58A 'is rotatable on a pivot l, .andis normally tilted, so that its nose '57 engages head"v a'ieaviv 62. The free end of the lever 58 is articulated to the wire I3 leading to the trigger mechanism, which may be similar to that illustrated in Figure l, or a suitable modication thereof. At about the middle of its length the firing rod 55 is enlarged at 63 and carries a pair of radial pins 6d on which are mounted rollers 65. The forward end of sleeve 54 carries a spiral cam 66 adapted to engage with rollers 65. The breech block 59 is keyed to sleeve 54, and the arrangement is such that when the breech block 59 is swung into closed position, the sleeve 54 is rotated and the spiral cam engages the rollers E and forces the Vliring rod 55 back, against the spring 59, until the nose of lever 58 engages under the head 56 and thus holds the firing rod in withdrawn or cocked position, ready for release by the trigger mechanism. When firing rod 55 is 'released its rear end strikes the end of rocking lever 56, by a spring 52 and thus drives the ring pin 5| forwardly into the percussion cap 0f the cartridge.`

As before, the breech block 50 provides a space 3 between the cartridge and the gas discharge outlet or outlets, and contains the perforated grid member 6. The gas filling the interior of the breech block has free escape to the atmosphere through a ring of slightly diverging expansion nozzles 61, and through a central expansion nozzle 68. This nozzle 68 is adjustable so that the escape of part of the -gases can be throttled by rotation in the bush 69, with which it has a screw thread engagement, so that rotation of the nozzle withdraws its inner end from its `seating 90 to an extent determined by the rotation of nozzle 68. This extent can be measured by the indication of a pointer 9| reading on a scale ring 92 carried by the nozzle 68.

The extractor mechanism is illustrated by Figures 10, 1l and 12. The extractor comprises a pair of curved arms or levers 93 lodged in recesses in the wall of the cartridge chamber, the ends of which act on the ends of extractor pins 94 covered by the rim of the cartridge case; The

lower ends of the arms 93 are rotatable on pivots I and their hub portions carry diametrcally opposite teeth or noses 95 which face in opposite directions. 'lhese noses 95 coact with projections or shoulders 95 on a pair ofV cams 91 integral with sleeve 54 and spaced apart to accommodate the lower ends of extractor levers 93 between them, with their planes at right angles to the planes of the levers. In consequence of this construction it follows that as sleeve 54 rotates with the breech block 55, as this is swung open, the shoulders 96 of cams 91 strike the noses 95 on extractor levers 93 and rotate both of said levers rearwardly, thus projecting the pins 94 outwardly and ejecting the cartridge case from the chamber.

The 3.45", 25 pounder gun illustrated by Figures 13 to 16 is mounted on wheels 19 and provided with the customary sighting equipment, and hand wheels 1I, 12, for elevating and directing the barrel. It also carries a trail 13 to which the breech end of the gun may be bolted at 14 for transport purposes. The end of the trail 13 carrying a suitable coupling eye or hook 14a, for towing purposes.

The gun in this case has a breech member 15 disposed between the grid chamber 16 and the gun barrel proper 11. which member is rotatable about vertical trunnions 19 midway along its length. The portions of the trunnions-shown in detail in Figure 16-which are engaged with the member 15 consist of bars 18, and the said bars are formed by two telescopic parts viz., a plunger 75 10 and an outer casing, with a spring 89 interposed between the parts as to make the bars 18 yielding as to their length, whereby a certain degree of longitudinal movement of the member 15 is permitted.

The breech member 15 is opened and closed by a handle 8| rotatable in brackets on the side of the member, and when the breech is closed 'the handle 8| occupies the position shown in dotted lines in Figure l4-i. e., pointing towards the rear end of the gun. On rotating the handle in a clockwise direction, its rst movement rotates a small crank 82, and through a connecting rod 83, applies pressure to a locking pin 84 which bears on the end of the barrel. The consequent reaction shifts the member 15 rearwardly, which is permitted by the spring trunnion bars 18, thus causing positive disengagement of the member 15 from the gun bore. Further movement of the f handle 8| carries the crank 82 past its dead centre position and withdraws lthe locking pin 84 from its hole in the end of the barrel, thus freeing the member 15 for rotary movement.

Continued movement of the handle 8l brings it up against a xed abutment 85 (Figure 14) on the side of the member 15, whereupon this member rotates about its trunnions 19 into the position shown in full lines in Figure 14 and dotted lines in Figure 15.

During the initial rotation of the member 15 a cam 86 on the trunnion axis bears on the tail of the lever 81, and through rod 98 moves the pivoted extractor levers 89 through a small angle of 6, thus loosening the cartridge case in the breech. As the member 15 swings into the fully open position the lever 81 strikes against a xed stop 90, and the extractor is then moved a further 12 to throw the shell case out of the breech.

The grid chamber 16 of the gun is tted with a ring of gas discharge nozzles similar to the 3.5" gun described with reference to Figures 9 to 12 and contains a perforated grid or cage of frustraconical form, as before, deiining a space between the inlet ends of the nozzles and the chamber space proper containing the propellant charge or cartridge.

This gun is intended to work with a high chamber pressure, in Acomparison with the 3.5" gun previously described which operates with a low chamber pressure.

It will be understood from the foregoing that in non-recoil guns according to this invention, in order to produce a given muzzle velocity the propellant charge and therefore the cartridge charnber of the gun must be considerably larger than in normal guns, in order to provide, in addition to the gases necessary to give the projectile the required muzzle velocity, the gases necessary to balance the recoil shock on the barrel of the gun. As previously mentioned the propellant charge may be made up of two separate charges one being of quick burning type and the other being of a slower burning type, the rate of burning of course depending, under equal pressure and temperature conditions, on the composition of the charge and its mechanical make-up, in wellknown manner.

Various constructions of guns for carrying the invention into practice have been hereinbefore described, but it should be understood that other constructions are possible within the scope of the invention. For example it is not essential for the gas chamber between the cartridge chamber and the rearwardly directed nozzles to be a coaxial rearward extension of the barrel or for said gas chamber to communicate with the cartridge chamber before firing. Thus a Aport may open into .the gun barrel, which port is Ainitially .Closed by the projectile, but Vas soon as Ythe pro- :jectile commences moving, is placed vint-o corn- Imunication with the .cartridge chamber space. The said .port may communicate by aconduit or passage constituting a gas chamber separaterom and substantially Aby the side .of the cartridge chamber, `With a rearwardly directed nozzle, which maybe tted with a -control valve to .control the rate offescape of .the gases and thus the amount of therecoil absorbed` The chamber space proper of .the 4gun is therefore enlarged by the initial movement of ,the projectile to include not only thev volume enclosed between the cartridge .and ,the base of the projectile, but also kthe volume ofthe gas .chamber between the cartridge and the Iear nozzle.

` In view of the fact that the present invention may be embodied in .guns having substantially diierent .breech constructions, the term "breech chamber has been used in the appended claims tomean that portion lof the gun which includes both the space in which the cartridge is received .when the gun is loaded and the :gas space into which the propellant gases flowv from the cartridge space through. a-,substantially Yunrestricted venting area and from which they pass to the'atmosphere through .one ,or more discharge members -of Vrestricted area.

What Iclaim is:

.1. A gun ofthe reduced recoil ltype comprising albarrel having a vprojectile-.receiving portion at its .rear en d, a .breech chamber including .a .cartridge space Vixedwto the rear end of the barrel in which .an explosive `propellant charge yis received when the gun is loaded, lthe rear wall of the .breech chamber supporting .at leastione rear- Wardly directed gas dischargemeinber having a, restricted ninlet and .an .outlet .open to the .atmosphere., part. .of said breech vchamber forward .-of the `rear Wall thereof and vadditional to. fthe Acan tridge space forming a gas vspace .of substantial volume Tin direct .communication with both the cartridge space and the inlet of said :gas `.discharge member, .said cartridge space haring a venting area into the gas space at least ,equal .to the cross-,sectional area. of the .barrel and vsaid gas space being so constructed andarranged .that

.i12 thegases developed by Acombustion of. the prope1 .lent .charge are free .to expand therein .when the .charge is ignited, the cross-sectional area ofthe inlet of said, gas/ discharge member being. .less kthan .th-at o'i said barrel.

12. Agun according to claim 1 wherein the cartriige space is disposed laterally of the axis Vvof the barrel. v

.3. Agun according to .claim 1 wherein the gas Vspace is coaxial with .the cartridge space.

4. .AV-gun according to .claim l including .a perforated .screen in .said ,gas `space interposed be tweennthe inlet .osaid rgas discharge. member .and the cartridge space.

l5. ,A giinkaccording to claim 4 wherein said ,nerforated Iscreen is of' substantially conical form and ihas `its .larger end disposed over the inlet of Vthe -gas Y.discharge member. v

.6. A .gun according to :claim 1 including. .an adjustable valve, associated with .said gas Vdis-- charge member for regulating the veiectiveffcrosssectional area of .thejnlet thereof.

",7.. ,A lgun according .to claim .l .Whereinsaid rgas discharge member Sin .the form ofan expanding gasuozzle` `.CPIAlLlilS .DENNISTOUN REFERENCES CITED The following references are of record in the me of thisvpaiten-t:

UNITED STATES PA'IENII'S OTHER REFERENCES fArmyQi-dnance, July-.August 1944, page 80,

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