US2483421A - Breech and firing mechanism for recoilless firearms - Google Patents

Description

Oct. 4, 1949. w. J. KROEGER ETAL BREECH AND FIRING MECHANISM FOR REGOILLESS FIREARMS I 2 Sheets-Sheet 1 FIG. 4.

Filed April 26, 1948 INVENTORS WILLIAM J. KROEGER. BY C. WALTON MUSSER.

TORNEYS fices in the gun's breech.

s e-we. 4 9 9;

PATENT OFFICE RECOILLESS FIREARMS William J. Kroege'r and Clarence Walton Muscat,

Philadelphia, Pa.

Application April as. ms. Serial No. same i cum. (on. as 111) (Grant amended The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

. The present application is a contination-in-' part of abandoned application Serial No. 536,590, filed on May 20, 1944, in the names of William -J. Kroeger and C. Walton Musser for Recoilless firearms, ammunition therefor, and ballistic design thereo Our invention coilless type, and recoil guns wherein relates to firearms of the reit has special reference to nonthe forces of rearward reaction that result from projectile discharge are neutralized by forwardly acting counterforces slmultaneously set up by the propellent charges combustion.

Broadly stated, the object of our invention is to improve the design and extend the usefulness of recoilless guns tralization is effected generated powder gas by a rearward escape of through openings or ori- A more specific object chamber and breech constructions for such recoilless guns.

Another object isto provide improved designs for breech orifice nozzles to facilitate orifice area adjustment and'the securing of zero recoil; at a desired performance level, and to neutralize gun twist with rifled barrels.

wherein the named recoil neu-- is to provide improved .A further object is to provide improved means for assuring substantially complete combustion of the powder .within the guns chamber, and for minimizing rearward discharge of unburned powder and fragments. w

A still further object is us provide improved means for firing the gun and for preventing the gun from being accidentally fired;

Other objects parent as the disclosure proceeds.

In the aforementioned parent application we disclosed a number of factors to be necessary for satisfactory operation of our inventive recoilless firearm. In constructing one recoiiless firearm pursuant to that disclosure we: gun's chamber of substantiallylarger diameter than the ammunition cartridge case which fits therein; (b) support this cartridge case centrally and description hereof ed under the m of March 3, 1888, as

ammo. ms; :10 o. a. 151) in this enlarged chamber solely from the two ends of the case; (c) provide in the gun's breech a rearwardly opening orifice of unique annular noz zle design and with ready adjustment for optimum area; (d) use a cartridge case having a metal wall which is perforated throughout the length and circumference of the case and which permits discharge of propellent combustion gases radially against the chambers surrounding wall and thence rearwardly from the gun through the annular orifice of the-gun's breech; (e) pre-engrave the projectiles for ready passage through the rifled bore of the gun's barrel; and (I) so coordinate the breech and firing mechanisms as to permit quick and convenient loading andflring.

The invention to which the present specification is essentially restricted is the specific breech closure structure used in thegun first disclosed by the aforementioned parent application. The present invention itself, together with illustrative embodiments thereof, will best be understood from the following description taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a view of the gun's rear end showing the breech block in its closed and locked position;

Fig.2 is a similar view except that the breech block is shown in the closed, unlocked position;-

Flg. 3 is also a rear view, but shows the breech block in the unlocked and open position, having been swung away clear of the chamber;

Fig. 4 is-a view taken from line 4-4 of Fig. 1 to show details ofthe orifice throat adjusting blocks plus other parts of the gun's breech and firing mechanisms;

Fig. 5 is a view taken from line 5-5 of Fig. 1

to show the internal construction and other de-- a Fig. 5 to show further details of the breech block id) make the military and the tappet housing support therefor; and

Figs. 7-8-9 are enlarged showings of the hammer's split safety fixture plus the slotted hammer and; hinge housing tubes therearound.

The complete recoilless gun Our inventive improvements are here illustratively disclosed as being incorporated in a weapon of 5'! mm. caliber capable of a completely recoilless firing of projectiles. As the will become apparent that our improvements may also be applied to'iirearms of sizes, characters and shapes other than the ones here disclosed and that the represented 57 mm. open-breech weapon thus has been chosen only to illustrate and not to limit the inherently wide application and scope by which these improvements are characterized.

The illustrative recoilless firearm here shown consists of a barrel I5; an enlarged chamber l8 secured to the rear of this barrel; a breech block I! partially closing the rear of the chambe a trigger handle l8 for the user's right hand by which firing of the weapon is controlled; a barrelhandle l9 for the user's left hand by which training on the target is aided; and a sight (not shown) for aiming the gun in aconventional manner.

As here represented. the guns trigger and barrel handles l8 and I 9 are suitably clamped around the barrel I 5 at the angularly spaced location shown by Figs. 1-2-3. Fig. 5 further shows trigger handle l8; barrel handle i9 is not there shown. but it is situated between the trigger handle and the muzzle (not shown) of the gun.

The chamber and breech As here shown, the guns chamber it takes the form of an enlarged cylinder which is afilxed at its forward end to the rear of barrel I5 in any integrally secure manner, as by the aid of screw threads (not shown). If desired, this connection may be rendered more permanent by a brazing of metal (not shown) around the entire circumference 'of the juncture. Such brazing constitutes a gas-tight seal which prevents damage to the threads from powder leakage therethrough; it also prevents relative turning between the barrel and chamber.

As the drawings also show, the guns breech block is a spider-like element removably secured within the rear end of chamber l6 and constitutes only a partial closure therefor. The breech block is actually an apertured supporting member on which are fixed certain vanes 52-58 whose form and function will later be described in detail. It takes the form of a cylindrical block I] which is radially spaced from the chamber walls in a manner to form a substantially annular orifice or venturi that leads from the chambers interior to the rear exterior of the gun. In Figs. 1 to 4 inclusive and 6 this annular orifice is shown at 22. As the drawings show, the annular orifice actually is interrupted by the four vanes 52-53; however, for all practical purposes the orifice acts as if it were a completely annular venturi as will later become evident, and therefore will herein be considered and referred to as such.

Four locking lugs 29 extend radially from this central breech block I! and interfit with mating protrusions 30 on the chamber wall interior. These mating parts have the form best shown by Figs. 1 to 4 inclusive and 6, and when engaged as in Figs; 1, 5 and 6 they securely lock the breech block I! within the rear of the chamber.

The chamber wall spaces which circumferentially separate the locking protrusions 30 have a diameter larger than the maximum for the breech block lugs 29, and this relation enables free longitudinal movement by those lugs through the spaces named. This movement is utilized in inserting the breech block into the chamber and also in withdrawing it therefrom, all in a manner to be described presently.

When inserted and locked within the chamber enlarged chamber I6 1. 5 and 6 the breech block I! constitutes a firm support for the ammunition (see Fig. 5) which it helps to position within the chamber. The steel of the block's central core structure is of suficient thickness and strength to withstand, with a factor of safety of. well over I, the maximum rearward thrust exerted thereon duringfirine.

Cooperating with the guns barrel and the Just described chamber and breech structure is ammunition having the unique perforated case shown in Figs. 4-5. As explained in greater detail in the aforementioned parent application, the purpose of the perforations 38 in the cartridge case 33 is to permit the powder gases to issue therefrom in a radial manner, so as to expand within the and become exhausted through the annular orifice 22 to the rear exterior of the gun with a torque equal but opposite in direction to that caused by a projectile upon being fired through the guns barrel.

In the loaded position represented by Figs. 4-5 the cartridge case head M is accordingly engaged by a mating recess 3i in the front of the breech block. This recess 3i flares outwardly toward the front so as more conveniently to receive the case head during loading. By its engagement with the head, the rear of cartridge case 33 is centrally positioned within chamber l6 and the entire case is restrained against backward move- 'ment. Thus positioned, the primer (not shown) carried by the cartridge case head M is engageable by a firing pin 42 protruding through the center of the breech block by firing mechanism later to be described.

The annular orifice and adjustable nozzle Recoilless firearms of the open-breech type here considered neutralize the forces of rearward reaction by forwardly acting counterforces. In

as shown in Figs.

our improved weapon these counteriorces are produced by acceleration of the rearwardly escaping generated powder gases with an accompanying pressure gradient within the chamber and venturi. Therefore, the pressure forces rearwardly acting against the obstructions presented by the breech can be counteracted by the forwardly acting pressure forces acting on the small annular forward portion of the chamber It, forwardly acting drag forces of the projectile (not shown)'in the rifled (not shown) barrel l5 and by the forwardly acting force component produced by the pressure of expanding gases in the conical and divergent portions of the earlier indicated annular orifice 22 between the guns breech block I! and thefrear wall of chamber I6 wherein this block is secured.

As illustrated in Figs. 1 to 4 inclusive and 6, this annular orifice extends all the way around that block's central core or hub and is obstructed only by the four radial vanes 52-53 which commence centrally from the common hub portion and terminate at their outward extremities in the breech locking lugs 29. All circumferential space separating lugs 29 thus constitute the named annular orifice 22 which leads from the interior of chamber l5 rearwardly to the exterior of the gun. I

Upon ignition of the propellent powder (not shown) and the resultant discharge of the projectile (not shown) forwardly out of barrel l5, there is expelled through the perforations 38 of cartridge case 33 combustion gases which are projected radially against the surrounding'chaml1 and there actuated ber wall and .thence outof orifice of the represented nozzle" shape. Start- I ing with a relatively narrow'radial width at its front or throat, the annular orifice flares outher through the ,annularorifice now being; de-' wardly toward therear with a total angle spread of approximately degrees; The exact value of this angle is chosen to yield the optimum of forward force component due to an expansion of :the powder gases in passing rearwardly through the orifice as earlier explained. 'I'oo narrow an angle is found to cut down the magnitude of this forward force component, while if the angle is made too wide, the gases seem no longer to keep contact withthe steepness Of wall separation and much of the desired nozzle eflect again is lost.

For maximum effectiveness it would be desirable to extend the annular orifice, to a substantial axial dimension, but practical considerations show that acceptable performance is achieved when the nozzle orifice has the relatively short lengths which the drawings indicate (see Fig. 4

in particular). Thus, we prefer to select for the nozzle an axial length which gives a rearor discharge area of approximately four times the area of the orifices front or throat area. Dimensions other than that shown may of course be utilized with varying degrees of relative efiectiveness.

In our achievement of complete neutralization of recoil we find that there exists an optimum ratio between the bore area of the gun and the throat area of the breech orifice. This ratio is dependent primarily upon the amount of expan- 4 sion obtained in the venturi 22 and to a lesser extent upon such factors as the relative weights of the powder and projectile. In a firearm of the annular orifice type here disclosed this ratio for As cut in the aforementioned application. we find it convenient in practice to mark oneach block the particular value of bore to throat area ratio which its use (along with a companion block of the same dimension) will give. Thus. one set of blocks will be marked 1.58; another 1.60; athird,1.62; and so on. Choice of the exact block size is most effectively determined by trial firings in a pendulum or other gun suspension which is free to swing and thereby indicate the presence, direction and magnitude of recoil, should same exist. In the illustrative 57 mm. weapon represented. zero recoil has been found to require the use of a pair of blocks which I give a bore-area to throat-area ratio of the order of 1.60. With such adjustment the nozzle throathas a total area which is approximately one-tenth of thecartridge perforation area.

Neutralization of rotational .reaction' Firearms with rifled barrels experience a rotational reaction by virtue of the spinning motion that firing imparts to the projectile. In the particular gun shown the gun barrel i5 happens to have been rifled (not shown) with a right-hand twist, the result being to give clockwise rotation toprojectiles fired therethrough, and this righthand acceleration of the projectiles mass'will impart counterclockwise torque of equal magnitude to the barrel. Our improved weapon includes provision for neutralizing such reactive torque by causing the explosive gases which rearwardly discharge through the annular breech orifice 22 to impart to the weapon counterbalancing torque of the same magnitude as that which zero recoil will lie within the range of about 1.35

to about 1.70.

recoil. In the illustrative arrangement disclosed,

this provision takes the form of a pair of orifice blocks 63 aifixed to flattened portions on oppos-l ing sides .of the inner nozzle wall and there firmly held by any suitable means such as the represented bolts 64 (see Fig. 4). with countersunk 55 heads. While occupying such aportion of the total orifice area as is needed to supply the necessary adjustment, these blocks 63 do not alter the basic nozzle shape thereof, and hence they constitute a particularly efficient means of effecting the required adjustment.

Themaximum throat area is of course realized when both blocks 63 are removed; hence the annular orifice is designed to afford a throat area large enough to meet the maximum requirements under that condition. Applying the figures earlier stated, this might give a bore-area to throatarea ratio of the 1.35 lower limit. To change 5 this ratio to its otherextreme of the named 1.70 maximum, it is merely necessary to install at 63 orifice blocks of size sufficient to cut down the total throat area by the requisite amount; and to obtain ratios of intermediate values there may be substituted adjusting block 68 of varying intermediate size.

the rified barrel imparts to the projectile (not shown). This provision is effected by so specially shaping the rear tail pieces of the breech block vanes 5253 that the gases passing through orifice 22 have angular momentum imparted thereto. (Of course, if the gun barrel happened to have been given a left-hand twist for its rifiing, the same result could be achieved by directing or shaping the vanes 52-53 in a direction opposite to that shown, thereby imparting to the rearwardly escaping gases. a clockwise torque which will counterbalance the counterclockwise rotation given by the gun to projectiles fired therethrough.)

As the drawings show, each'of these breech block 'vane tailpieces tapers in the general manner shown from a maximum cross section beneath locking lugs 29 rearwardly toward a minimum and much narrower width at the rear ex-p treme thereof. If this taper were the same on both sides of each tailpiece, the discharge of powder gases therepast would exert no rotative force ,in either direction, but instead the side force components set up by the expanding gases would be the same in both directions and hence completely counteract one another.

To obtain the desired torque neutralization we modify the tailpiece flaring to the extent indicated by the drawings. From those drawings it can be seen that the angle on the one side of each tailpiece differs from the angle on they other side in the proper amount and direction to give the gases a counteracting spin about the gun axis.- The effect is to impart to the axes of breech orifice opening 22 small angular displacements (all in the samerotative sense) with respect to the main axis of the guns barrel l5 and chamber [6.

In consequence, the sides of these vanes having the smallest angle have imparted thereto a stronger side or tangentialthrust from" the expanding gases than-do the opposite vane sides, andthere thus is imparted to the breech block a torque-counteracting that applied by the pro- Jectile. Only the relatively small degre of angular unbalance indicated is found sufilcient to make the thus imparted torque of the same magterclockwise rotation moves the locking lugs out nitude as the barrel l imparts to the projectile (not shown) in advancing it through the rified bore.

During firing the breech block I! transmits this neutralizing torque to the chamber and thence to the barrel, and in this-way all forces of rotational reaction are neutralized in a very simple, yet highly effective manner. In the illustrated weapon the-combustion gases that fiow rearwardly through the breech orifice openings 22 have imparted thereto a counterclockwise spin which is opposite to the clockwise spin given by the gun's right hand rifling (not shown) to the forwardly fired projectile (not shown). As the vane structure of the nozzle-forming portion of the breech block is asymmetric in relation to the gun's axis for each Venturi opening, a different amount of expansion tends to occur for opposite sidesof each venturi for axial gas flow. Therefore, the center line of the gas flow through each nozzle is tangentialiy diverted'in a circular pattern about the axis of the gun. The accompanying gas reaction" torque exerted on the gun-is clockwise and thus neutralizes the counterclockwise projectile reaction" torque received by the barrel IS.

The breech block carrier and lock mechanism Explanation has already been given of how the breech block I1 is secured in the rear of chamber I 6 by the aid of that block's locking lugs 29 and the mating protrusions 30 on the chamber interior. In the locked position represented by Figs. 1, 5 and 6, this support is all that is needed to hold the breech block in place, and it is fully adequate to restrain the maximum chamber pressures which combustion of the propellent charge (notshown) sets up.

To facilitate loading, and removal of the cartridge case 33 after firing, provision is made for unlocking this breech block l1, rearwardly withdrawing it from the chamber l6 and swinging it out of alignment with the chamber interior to some downward position such as that shown in Fig. 3. Aiding these actions is an operating member which illustratively takes the form of a pair of handles 49 which protrude from the breech block, a radial support member shown in the form of a tappet housing '50 which extends into that blocks center, and a lateral support member shown in the form ofa hinge housing 5| (see Fig. 5) which interconnects the radial member 50 with the outside of the gun's chamber l6. These elements constitute mechanism by which the breech block continues to receive support from the gun after it has been withdrawn from the chamber.

The named operating member represented in the drawings by handle 49 protrudes in the manner shown from radial vanes 52 which extend rearwardly from the breech block I1 by a distance somewhat greater than do the remaining two breech block vanes 53. By these handles 49 an operator may rotate the breech block through the small angular distance indicated at d in Fig. 6. In the gun here shown this range of angular movement is of the order of '35 degrees.

Clockwise rotation serves to engage the breech block locking lugs 29 behind the mating protrusions 30 of the chamber and thereby secure the breech block therein as earlierexpl'ainedf counof engagement with the chamber protrusions and into the circumferential regions between protrusions. In the latter position the breech block I! is free for rearward withdrawal from the chamber.

Serving to support the breech block upon such withdrawal is the radially disposed tappet housing earlier mentioned. This housing is attached at its outer end to a pivot tube or hammer 110118? ing sleeve 56 sliding and turning in the stationary hinge housing or support tube 5| earlier mentioned as being fixed to the outside of chamber I 6; from this attachment the radial tappet housing extends through a cutaway portion in a rear rim 51 of the breech block to that block's center where the sun's firing pin 42 (see Fig. 5) is mounted.

There, circular openings in the front and rear of this radial member 50 accommodate opposing bosses 58 and 59 (see Fig. 5) projecting from the breech block and from a cover plate 50 therefor. This cover plate is'secured to the block by the aid of three bolts 6i which pass through the plate and into tapped openings in the block metal thereby holding the plate firmly in a mating recess in the block's rear rim 51. v

The rotatable connection thus established permits the earlier named angular movement of the breech block II with respect to the chamber l6, and also with respect to the tappet housing 50 which extends into the block's center from the chambers outside. In this way application of clockwise turning force of handles 49 effects locking of breech lugs 29 behind the mating protrusions 30 of chamber l6; and application of counterclockwise turning force disengages those lugs from the chamber protrusions and thus frees the breech block for rearward withdrawal from the chamber. Both of these turning movements are limited in their extent by the sides of the represented opening I05 in the wall of the rear breech rim 57.

As aforesaid, the illustrated weapon is represented as having right-hand rifling (not shown). In such a weapon, the gas forces applied (as earlier explained) to neutralize torque reaction exert thereby maintain the locked position thereof during firing. Where the gun can be rifled with lefthand twist, then the locked position of the breech block should of course be at its counterclockwise limit of turning movement.

The earlier named hinge housing sleeve 5| is secured to the outer wall of chamber i6 by brazing or other permanent form of attachment. This hinge housing is continued forwardly to the trigger handle I8 and within it the smaller diameter hammer housing sleeve 56 is carried (see Figs. 5 and 8) in a manner permitting both radial and lengthwise movement. This form of carriage permits the affixed tappet housing 50 to bewithdrawn rearwardly with respect to the hinge housing 5| and also to be rotated with respect thereto.

Once, therefore, breech block I! has been disengaged from the chamber portrusions 3!], application of rearward force to handles 49 causes the breech block l1, tappet housing 50 and hammer housing 56 all simultaneously to be moved back away from the rear of chamber It.

The range of this backward movement is sufiicient to allow complete clearance of the breech block with respect to the chamber, and when this housing'may both be swung downwardly'to the position shown in Fig. 3. In such position the entire interior area of the chamber I6 is un-' obstructed in a way permitting ready insertion of the projectile (not shown) and cartridge case 33 into the gun, or ready withdrawal of aflred a cartridge case from the gun's chamber.

To re-insert the breech block into the chamber it is merely necessary to swing the tappet housing 50 clockwise and upwardly about its in which the locking lugs 29 thereof engage with the chambers mating protrusions (as best shown inFigs.1and 6). y

Close fitting of the radial tappet housing 50 against the end of the hinge housing 5| when the breech block I1 is locked within the gunschamber may be secured-in any desired manner such as by the aid of shims of the type shown at 66 in Fig. 1

:The firing mechanism For igniting the ammunition propellent charge (not shown) atthe will of an operator, use may closed). Here represented by way of illustration is a unique mechanical type of firing mechanism by the aid of which an operator may fire the weapon by a simple squeezing of the trigger handle Hi. In the disclosed arrangement, the

firing pin fl-carried by the gun's breech block l1 (see Fig. 5) receives through a tappet 51, a firing blow created by the rearward movement of-a rod-shaped hammer 6 8. The force incident to this rearwardmovement originates in a compression spring 59 and is made available for firing the gun when a trigger 10 protruding from the front of trigger handle I8 is compressed into that. handle. 7 a

The just named tappet 51 (see Figs. 4-5-6) is mounted on a rocker pin 1| within the radially disposed tappet housing 50; As earlier described this radial member 50 also constitutes the support for the breech block |1 when withdrawn from the weapons chamber l6; serving to close the housings back isa removable'cover-13 held in place by an overlapping of the breech block cover plate '50. A tappet retractor spring 14 urges the outer end of. this tappet tothejorward travel limit shown in Fig. 5, and in that condition the inner. end of the tappet is separated from the rear of firing pin 42 by-the substantial" clearance which Fig. 5 also shows.-

'The illustrated hammer 68 takes the form of a long, slender rod of steel or other suitable metal slidably contained (see Fig. 5) within the housing sleeve 56 earlier described as constitutinga support for the outer. end of the radial tappet housing 50. As earlierexplained, this housingsleeve or pivot tube 56 is-rotatably and slidably concondition is realized the breech block and tappet companion hammer housing 56 likewise e :tends 'within the stationary hinge housingil from the rear location-of tappet housing 50 to the forward location of trigger handle it. At the said forward location the housing or pivot tube 58 terminates in a spring retainer 15, taking the form of the represented sleeve attached to the tube end by a thread connection. At the rear end the hammer is slidably supported by a ham- 10 mer bushing I05.

5 within the space thus made available. The for- The inside diameter of the hammer housing 551s somewhat larger than the outside diameter of the hammer rod which it surrounds, and

the earlier named hammer spring 69 is carried ward end of this hammer spring abuts against the retainer 16, while the rear end of the spring exerts force against a spacer sleeve 11, also slidably carried between the central hammer 68 and the housing sleeve 56 which surrounds it.

of length greater Adjacent to this spacer 11 on the side opposite to the spring 'is a reduced diameter section of the hammer 5'8, and surrounding it is a split safety fixture made up of two parts 19- 80 5 (seeFigs. 5 and 7) having the mating character shown in the drawings.

These two parts are housed within the hammer tube 56 for restricted slidable and rotative movement, and they also permit the hammer 88 to move axially there 3 through along the hammers reduced diameter be made of any suitable firing mechanismoeither s electrical (not shown) or mechanical (here dis I portion. v

Radially protruding frompart 19 is a safety arm 8| which extends through registering slots 52 and 55 in the concentrlcallydisposed hammer and hinge housings 56 and 5|, respectively, to the outside for manipulation by the operator. The named slots 62 and 55 have .the character illustratively shown in enlarged form by Figs. 8 and 9, andduring cooking and firing of the 40 hammer rod 58 theseslots cooperate with the safety arm 8| in a manner to-be explained presently.

The slot 55 in the outer'or hinge housing 5| has the substantial width later named and is than the axial distance through which hammer 68 and safety arm 8| ,move during cocking and firing. The cooperating slot 62 in hammer housing'56 is comprised of two parts identified as 52A and 623 (see Figs. 8-9)- This slot 62 is wide at its front (62A) and narrow 5!! enable the safety fixtures at its rear (52B) and has 'on the narrow side thereof a total length somewhat greater than that of housing 5ls slot the wide region of this hammer housing slot is sufficiently long to 19-80 to be inserted therethrough for assembly around the reduced diameter portion of hammer 58. This hinge housing slot 55' and the hammer housing slot 52 at its widest section (see Fig. 8) both have 50 a total circumferential width of somewhat more than 90 degrees. In cooperation with safety arm 8| these two slots serve to restrain the downward swinging movement of the tappet housing 5ll'(see Fig. 3). to an angle ofionlyslightly more 65 than that 90-degree limit.

tained within .the outer hinge housing tube 5| It" will be seen from the drawings that the Under the after loading conditions represented in Fig. 5 the hammer 58 is cocked to the forward position where a latch head 83 thereof is advanced past trigger 10s sear 84; the hammer (0 spring 59 is compressed between hammer housing 55's forward retainer 16 and the rearward spacer 11; that spacer abuts parts 19-80 and through them is held against rearward movement by engagement of sa'f'ety'arm 8| with the hammer housing 55s short lower recess 12 (see Fig. 8);

hammer.

- 12 of the short slot 62A in tube 56 (see Fig. 8)

and rotated upwardly into alignment with hammer housing 56's long slot 623. This permits the 'spring 69 and spacer H to push the safety fixture '|980 backwards to the point where the rear thereof abuts the larger diameter of the hammer 68. That hammer now receives the rearward force of the spring and pulls latch head 83 against the trigger sear 84 (see Fig.

Under these conditions a compression of the trigger into the housing l8 therefor will release the hammer allowing the compressed spring rapidly to move it backwardly along with spacer I1 and the safety fixture. By this movement the safety arm 8| moves in the narrow slot 823 of housing tube 56 to the rear limit thereof. This limit is reached just before the end of hammer 68 has contacted tappet 61, and at that point the springscompressive force is removed from the The momentum of acquired motion causes the hammer to continue to move back through safety fixture 79-80 and by striking the outer end of tappet 81 to impart a blow to the firing pin 42 and thereby detonate the primer (not shown) inthe cartridge case.

. nism is returned to the original or "after load- To re-cock the hammer in preparation for the firing of another round, the breech block I? is by counterclockwise rotation disengaged from the chamber 56 and rearwardly withdrawn by handles 49. Tappet housing 59 transmits this rearward movement to the hammer housing 56 and pulls retainer '56 backwards in the stationary hinge housing 5|. Safety arm 8i, now abutting (see Fig. 9) the rear of hinge housing 5ls slot 55, restrains the spacer if from rearward movement, and in consequence, the hammer spring 69 now becomes compressed.

By this rearward movement the narrow slot- 62B in hammer housing 56 is drawn past the safety arm 8| into a position of housing 58 where that safety arm is in the area of housing 56s wide forward slot 52A. Incident thereto is a complete clearance of the breech block 81 from the end of chamber i 6, and a resultant freedom of swinging movement of this block downwardly to the position shown in Fig. 3.-

Such a swinging of tappet housing 56 rotates the hammerhousing 56 counterclockwise in the stationa y hinge housing 5|. During this rotation of the hammer housing 56, the safety arm 8| continues to abut the rear of hinge housing 5 as shown dotted by Fig. 9, and thus the recess 12 in the short slot 62A of housing 56 (see Fig. 8) is b ought into alignment with that arm. Release of breech block withdrawing force now allows the hammer spring 69 to pull the hammer housing 56 forward and thus re-engage this housings short slot 62A recess 12 with arm 8|, as shown by Fig. 8. Subsequent swinging of the br ech block and the tappet housing 50 inwardly (clockwise) into alignment with the weapons chamb r rotates housing tube 56 and safety arm 9| clockwise in the stationary hinge housing 5|. He the breech se ted into the end of chamber l6 by movement w ic carr es hammer, housing 55. safety arm BI block may be forwardly rein sive blow to thefiring pin ing" condition of Fig. 5 with which this description started.

Firing pin, leader's and trigger safeties The gun operator's or "loader's safety has already been described in part. It utilizes the safety arm 8|, which at the. end of each cocking occupies the after loading position shown in Fig. 5. With the safety arm 8| in this position pulling of the trigger I9 is ineffective for releasing the hammer, and no firing of the weapon is possible.

Before the weapon can be fired it is necessary for the loader of the gun to push safety arm 8| forward out of housing tube 56's slot recess (see Figs.'8-9) and rotate it counterclockwise into alignment with that tube's long narrow slot 623, thus effecting the "armed position (not shown). When that has been done the compressive force of hammer spring 69 is transferred to the trigersear "84, and withdrawal thereof from the latch head 83 allows the hammer to fly backwardly'and cause tappet t'lto impart a percus- 2.

In addition to this loaders safety, our improved weapon here disclosed also includes: (a)- a trigger safety; and (b) a firing pin safety.

The trigger safety utilizes mechanism asso-. ciated with the trigger 10 within the trigger handle l8. This trigger is mounted for rotation about a support point 86 (see Fig. 5), and the lower portion of the trigger is held forwardly by, a leaf spring 81. This spring urges sear 84 upwardly into engagement with the hammers latch head 83.

The trigger handle l8 comprises two sections fastened to a carrier member 94 which is fixedly mounted on barrel l1. Also carried by the trigger handle I8 is a trigger guard 89, which completely surrounds the exposed portion of trigger i0 and requires that pulling movement be imparted to the trigger through application to this guard. A fastening ferrule 90 for this guard is borne by the carrier member 94 slightly below the corresponding support 86 for the trigger.

The trigger safety fixture is fully described in the aforementioned parent application and therefore needs no complete description here. It

. by a trigger safety spring (not shown). Key 92 fits into a mating slot (not shown) in one side of the trigger guard 89 and is prevented from rotational motion by fitting into the slots in the stationary central plate 94 of the trigger handle. As long as the safety button 9| protrudes from the side of handle I 8. the just mentioned spring (not shown) holds half of this non-rotating locking key 92 in the slots (not shown) in the guard condition the guard is locked side 89. Under this against rearward movement into contact, with trigger 10, and application of pressure to the guard 89 is prevented from effecting trigger operation.

When, however, the safety button 9| .is depressed the locking key 92 is moved completely within the handle plate 94 and out of engage-' ment with the trigger guard 89. Under this condition the guard is freed for backward movement and'application of pressure thereto then becomes effective for pulling the trigger and firing the weapon. In view of the fact that the safety spring (not shown) is continuously acting as aforesaid to move the safety button 9| into the safe position, the button must be kept depressed by the gunner during the entire'time it is desired .to keep the trigger guard 83 free for actuation of the trigger. Y

The third or firing pin" form of safety involves the hammer tappet 61 and engagement of the 'inner end thereof with the 'firing pin 42 carried by the weapons breech block II. Surrounding the end of this firing pin is the rearward boss 58 (see Fig. 5), earlier described as fitting intoa mating opening in the inner end of the tappet housing 50.

In order that the tappet 31 may strike the firing pin, this circular boss 58 is provided with the slots 65 represented in Figs. 4-5. When properly aligned with the tappet this slot permits such forward movement thereof as is necessary to impart a detonating blow to the firing pin.

. This proper alignment (as shown in Fig. 4) exists only when the breech block I I is locked within chamber It by clockwise rotation of lugs 29 behind the chambers mating protrusions 30.

, When the breech block's lugs are disengaged from.

the chamber, this breech boss 58 is rotated to a position where the described slot therein no longer aligns with the tappet, and under this condition the boss wall mechanically blocks advancement of the tappet into contact with the firing pin.

Hence, even though thebreech block I I may be inserted into the chamber it is possible to fire the weapon .only after there has been imparted to that block sufficient clockwise rotation to effect secure locking in the firing position.

Loading and firing From the foregoing it will be seen that we hav provided an improved recoilless firearm which ofiers special advantages in connection with both jdetonation of the primer and ignition of the charges contained within the cartridge case..

The resultant combustion of the propellent charge (not shown) discharges the projectile (not shown) and at the same time ruptures a frangible lining 33 (see Figs. 4-5) which lines the interior breech venturi and thence to the rear of the weapon. In a manner already explained inpart, this escape of explosive gas-sets up counteriorces which neutralize recoil and thus permit the weapon to be fired either from the shoulder or from a light tripod or other'mounting.

The perforated wall metal of the cartridge case 33 remains intact during this firing and is not ruptured or otherwise damaged. Indications are that, the pressure within the chamber IS on the inside and outside of the cartridge case wall.

equalizesjitself early during the burning cycle.

, chamber.

loading and firing. To place the ammunition round within the weapon it is merely necessary to unlock the breech block I! by turning it counterclockwise from the Fig. 1 to the Fig. 2 position, withdraw it from chamber l6 and swing it downwardly to the position shown in Fig. 3, thus completely freeing the chamber opening.

The ammunition round is now inserted into the opened chamber and the rear of the barrels bore. When the projectile (not shown) is positioned in the barrel bore (not shown) centering support is imparted to the entire cartridge case 33 and allows the rear head 4| thereof to droop only slightly from the rear chamber center. The breech block I! is now moved forwardly into the chamber. In approaching and engaging with the cartridge case head II, the flared recess 3| in the breech block's front serves to center the head thereby constituting a second support for the cartridge case. Clockwise rotation of the-breech block by handles l9'now locks it into the chamber with the front shoulder (not shown) of the case in abutment with the barrel, and the case head ll in abutment with-the breech block, the primer (not shown) in alignment with the firing pin 42 and the entire cartridge case 33 centrally positionedwithin the surrounding chamber I6.

Thus, after the case has been fired, some of the openings 38 may be found to have thin films of ash either partialiyor completely covering their area.

Subsequent withdrawal of the fired cartridge case from the chamber is effected by unlocking the breech block, withdrawing it rearwardly, and swinging it downwardly out or register with the This frees the fired case for ready withdrawal from the chamber and conditions the weapon for insertion andsubsequent firing of another ammunition round.

Summary I From the foregoing it will thus be seen that we have so designed and extended the usefulness of non-recoil guns wherein the forces of rearward reaction that result from projectile discharge are neutralized by forwardly acting counterforces simultaneously set up by release of powder gases through an orifice in the guns breech; that we level; that we have assured substantially complete combustion of thepowder within the guns 'chamber and have minimizedthe rearward discharge of unburned powder and fragments; and

The weapon is now ready for firing, and'upon that we have provided improved means for firing the gun andfor preventing the gun from accidentally being fired.

Our inventive improvements thus are capable of wide application and hence are not to be restricted to .the specific form here shown and described by way of illustration. a

We claim:

1. In a firearm, the combination of a barrel, a

chamber communicating therewith, a breech block movable into and out of the rearward portion of said chamber and rotatable for locking engagement therewith, coacting interlocking members formed on peripheral portions of said breech block and the inner wall of said chamber engaging said support for movement lengthwise of said chamber and barrel, and means extending radially from said breech block to said companion member and constituting a connection which permits rotative movement of the breech that block when same is withdrawn from the chamber. g

2. In a firearm, the combination of a barrel, a

assa'aai means effective to engage said hammer and latch it in' its said cocked position against the force I block within the chamber and which supports chamber communicating therewith, a breech block movable into and out of the rearward portion of said chamber and rotatable for locking engagement therewith, coacting interlocking members formed on peripheral portions of said of said spring.

5. In a firearm, the combination of a barrel, a

chamber communicating therewith, a breech block movable into and out of said chamber, a firing pin in said breech block, a support tube secured to the outside of said chamber and extending lengthwise thereof, a pivot tube within said support tube carried thereby and free to Slide and turn with respect thereto, a radial member connecting said breech block and pivot tube whereby movement imparted to said block is transmitted to said pivot tube, a tappet arm carbreech block and the inner wall of said chamber and being engageable and disengageable upon locking and unlocking rotations of the breech block within the.chamber, a support for said breech block secured to the outside of said chamber, a companion member rotatively and slidably engaging said support for movement lengthwise of said chamber and barrel, a radial member extending from said breech block to said companion member and constituting a connection which supports the breech block when same is withdrawn from the chamber and which also permits the block to be rotated when within the chamber, a firing pin disposed in said breech block, a tappet arm carried by said radial memher and spannin the spacebetween the axis of the firing pin and the axis of the supports said companion member, and a hammer element movable axially of said companion member to strike said tappet arm and operate said firing pin.

3. In a firearm, the combination of a barrel, a

chambercommunicating therewith, a breech block movable into and out of said chamber, a supporttube for said breech block secured to the =0utside of said chamber and extending lengthwise thereof, a pivot tube within said suppfirt tube carried thereby and free to slide and turn with respect thereto, means operatively connecting said pivot tube to said breech block whereby movement imparted to the block is transmitted to said pivot tube, a firing pin in said breech block, a tappet arm carried by said connecting means and extending betweenthe axis of said firing pin and the axis of said pivot tube, and a I hammer disposed within the pivot tube and movable axially thereof to engage said tappet arm transmitted to said pivot tube, a firing pin in said breech block, a tappet arm carried by said connecting means and extending between the axis of said firing pin and the axis of said pivot tube, a hammer disposed within said pivot tube and movable axially thereof between a forward cocked position and a rearward released position .where the hammer engages said tappetand thereby operates the firing pin, a spring also within said pivot tube for urging said hammer from said cocked to said released position, and trigger ried by-said radial member and extending between the axis of said firing pin and that of said pivot tube, a hammer within said pivot tube movable lengthwise between a forward cocked position and a rearward released position where the hammer engages said tappet and thereby operates the firing pin, a safety fixture carried by said hammer and protruding through registering slots in said pivot and support tubes, a hammer spring within said pivot tube compressible between a forward extension of the pivot tube and said safety fixture, means including said fixture and the said tube slots through which the fixture protrudes for causing rearward movement of said breech block and pivot tube to compress said hammer spring, and a trigger eifective upon forward return movement of said breech block and pivot tube to engage said hammer and latch it in its said cocked position against the compression of said spring.-

6. In a firearm, the combination of a barrel, a chamber communicating. therewith, a breech block movable-into and out of said chamber, a firing pin in said-breech block, a support tube secured to the outside of said chamber and extending lengthwise thereof, a pivot tube within said support tube carried thereby and freeto slide and turn with respect thereto, a radial .member connecting said breech block with said engages said tappet and thereby operates the firing pin, a fixture carried by said hammer and including a safety arm which protrudes through registering slots in said pivot and support tubes, a hammer spring within said pivot tube compressible between a, forward extension of the pivot tube and said hammer fixture, means ineluding said fixtures safety arm and the said tube slots through which that arm protrudes for causing rearward and swinging movement of said tube-supported breech block to compress said hammer spring and for causing forwardreturn movement of the block to engage said arm in a safety notch in one side of said pivot tube slot, and a trigger efiective upon manual movement of said safety arm out of said notch to engage said hammer and latch it in its said cocked position against the compression of said spring.

7. In a firearm, the combination of a barrel, a chamber communicating therewith, a breech block movable into and out of said chamber and engageable therewith and disengageable therefrom upon locking and unlocking rotations with firing pin, a hammer movable to strike the tappet 10 and operate said pin. resilient means normally urging the tappet am away from the firing pin, and means mechanically positioned beside said protruding pin to permit contact thereof by said tappet when and only when said breech block occupies its locked rotative position within the chamber.

WILLIAM J. KROEGER.

CLARENCE WALTON MUSSER.

No references cited.

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