US2339661A - Breech mechanism for automatic firearms - Google Patents

Description

Jan. 18, 1944. w. l.. swARTZ BREECH MECHANISM FOR AUTOMATIC FIREARMS Filed Jan. 17, 1940 Patented Jan. 18, 1944 2,359,661 y BREECH MECHANISM Foa AUTOMATIC i FIREARMS William L. Swartz,`Weathersfieltl, Conn., assigner to ColtsPatent IFire Arms Manufacturing-Com- "pany, Hartford, Conn., a corporationy of Connecticut Application January 17, 1940, .SerialNm y314,272

The present invention is particularly applicable. to ,automatic firearms of the type shown in Patent No.,1,1525,065 to John M. Browning and in Patent Nc. 1,852,057 to Frederick T. Moore and Christian Pfeiffer, but it is not so limited.

The principal object of thepresent invention l.is to yprovide improved .means for preventing mpVementof the `transversely movable breech block, .during that period in the Acycle of operation .of the gun when the blockis intendedto be in .its `lower position.

`In the accompanying drawing I have shown the embodiment of the invention which I now deem preferable, but it will be understood that the `drawing .is Jintended for illustrative purposes onlyand' is not to be construed as defining or limiting the scope of the invention, the claims forming ,a part of this specification being relied upon for that purpose.

' Of theI drawing:

l1 isa fragmentary side view of a gun embodyillgy the invention, a certain portion being broken away to show vinterior parts.

Eig, v:1L-is a fragmentary vertical sectional view taken along the line 2-.2 of Fig. 1 but omitting certain parts.

Iteferring to the drawing, .I represents the main casmg which .comprises `spaced side plates .connectecl near their front ends with a trunnion block 2, `In the drawing only the right hand side plate Ia isshown. At .the top of the casing is afeed box .3 .and .at the Irear of the feed boxis .a trigger kli.V These .parts need not .be described in detail `as the invention does not relate to the detalsof the feed mechanism or of .-the firing mechanism. At the front and rear of the feed box are cover plates 5 and 6 which connect the .side plates.

The barrel-1 is longitudinally movable in an openingin .the `trunnion block and it is detachably connected with a barrel extension 8 which is 1ongitudinally movable in the casing, being guided at the top and at the bottom .by inward pro- .ecting anges on the side plates. 'Ihe barrel extensioncomprises two spaced -legs 8e and 8b. The barrel-and Ybarrel extension move rearward upon recoil andarereturned in the forward direction by the recuperator .spring 9. This spring acts through the recuperator rod I Il which -is connected atits rear end with a depending lug `8c on the barrel extension 8.

.A150 longitudinally movable within the casing is a lock frame .I I, this frame being shown in Fig. 1 'in-the rear-ward position, which it occupies at least momentarily after the .ring of each shot.

2 Claims. (01."89-3) Depending from .the lock frame II is a yoke I2 to which are connected two transversely spaced tension rods I3. The depending lug .8 of the barrel extension 8 carries a yoke I4 having laterally projectingarms Ma (one of which is shown in Fig. 1*).v Supported in part on the arms I fla are tubes l5 which receive the tension rods I3 and which .also receive reaction .springs lli surrounding `the tension rods. 'These springs abut at their rear ends against plugs I5ab in the rear ends of the tube, andabut at their forward ends FAX against projections (not shown) on the rods I 3 near the forward ends thereof.

Upon recoil, the barrel., barrel .extension and lock ,framemove rearward simultaneously, and the lock frame is at least momentarily held in its rearward position asjshown in Fig. 1. The barrel and barrel extension immediately move forward under the influence of the recuperator spring il,y as already stated, and the tubes l5 move forward at the same time, thus compressing the springs "I6, and tensioning the rods I3. Upon subsequent Yrelease of the lock frame, thesprings I6 ,in cooperation with the rods I3, move the lock frame forward, this frame with its associated parts serving to push a cartridge into the chamber of the .barrel as `explained in detail in the aforesaid patents.

`A breechblock Il is provided whichmoves bodily withthe barrel-extension 8 and which is also movable vertically with respect to the barrel extension, being positioned .between the legs Ba and BD and being guided by ribs 8d and 8B. The vertical movement of the breech block Il is effected by an actuating lever I8 which is carried by the lock frame II and which ismoved about its pivotal connection I8a by means `of a cam structure indicated in its entirety by I9 and depending from the main casing at the left side thereof. The aetuating leverA I 3 has transversely projecting studs 18h which are adapted to enter a T-slot I la in the breech block. lWhen out of engagement with the actuating lever, the breech block I1 is retained andsupported by a-stop 2,0, shown in Fig. 1. The stop 20 has a fiat surface on its top upon which the bottom surface of the breech block rests when it is in lowered position so that the breech block will be properly positioned whereby the studs I 81J will accurately enter the T-slot I'Ia during functioning of the gun to avoid jamming.

When the lock frame moves forward from the Position shown in Fig. 1, a cartridge is pushed into the chamber of the barrel, as already stated. At the same time, a stud at I8 on the left side oi the actuating lever I8 travels along the cam groove me until it reaches the position shown by dot-and-dash line in Fig. 1. In this position the studs I8b on the actuating lever are about to enter the T-slot I`|a in the breech block. Continued forward movement of the lock frame and of the actuating lever causes the stud 'IIBc to move downward along the cam groove |9b thus rotating the actuating lever in the counterclockwise direction and moving the breech block upward to its breech-closing position where it serves as an abutment for the cartridge.

Upon recoil, the barrel and barrel extension and the lock frame initially move rearward in unison and during such movement a stud at ld on the left side of the actuating *leverl Vengages the cam surface |90. This engagement of the stud I8d with the cam surface |90. moves the lever IB in the clockwise direction and the lever in so moving causes downward movement of the breech block.` This clockwise movement of the lever I8 carries the stud I8c into the cam groove |96. Continued rearward movement causes the stud |8 to move. past the spring-pressed switch |9 until the parts finally reach the position shown byrfull lines in Fig. 1. It will be understood that just before the lock frame and the associated parts reach the fullline position shown in Fig. 1, the barrel and barrel extension and associated parts, start to move forward to the position shown in Fig. 1, .this forward movement separating` the breech block fromthe actuat-v ing lever I8.

Further and more detailed illustration and description of the operating mechanism for the breech blockv are to be found inthe before-mentioned patents, and the foregoing brief description is sucient for purposes of disclosing the present invention.

It is highly desirable that the breech block be readily removable from the gun for inspection, cleaning or replacement. In order to permit such ready removal, the stop 20 is relatively movable in the direction shown in dot-and-dash lines in Fig. 1, and it ispivotally connected at 2|]EL with the yoke i4. The stop is normally held in its upper operative position by a manually releasable means such as a spring-pressed detent 2|. When the detentZl is withdrawn, the stop 20 can move to its lower inoperative position as shown by dot-and-dash lines in Fig. 1. This re y leases the breech block I1 and permits it to dropl downward entirely out of the gun.

The breech block l1 can be put in place readily without interference by the stop 2|),` and after it is in place the stop can be restored to the position shown by full lines in Fig. '1, the stop thus again retaining the block.

The movable stop 20 yand the detent 2| do not of themselves constitute any part'of the present invention, these being shown and claimed in the co-pending `application of George Webb for Breech mechanism for automatic firearm, Serial No. 314,271, filed on even date herewith.

It will be observed that with thev breech block in the position shown in Fig. 1 the yslot |'|n is properly positioned to receive the studs I8 on the actuating lever I3 as xthe said lever moves forward. During lfiring, the gun is subject to some vibration which might take the breech block out of the position shown in Fig. 1. During operation, the gun is not always in the horizontal position as lshown, but it may be in an' inclined position or may even be in an inverted position. Under all possible conditions of use it is essen-f tial that the breech block be in the position shown in Fig. 1 at the moment when the forward move ment of the lock frame is about to effect the en trance of the studs ith into the slot Ha. To pre vent movement of the breech block out of th position shown, a suitable means is provided suc] as the spring-pressed detent `21| shown clearly il Fig. 2, As shown, -this is', mounted in an apertun 2da in the left leg 8b of the barrel extension, am is adapted to engage an upper edge portion o the block The detent 24 is provided with 1 shoulder Zeb adapted to abut a seat 24c in thl aperture 2te to operatively position the deten so that the inner end thereof may be in posltiol toiengage, but preferably and normally exert nl vappreciable pressure on, the upper edge of on side of the breech block. The detent 24 is pressez into its operative position by means of a sprinl 25 which abuts against a plug 26 threaded int: the aperture in the barrel extension leg. Thil detent serves to resist movement of the breecl block i 'i upward out of its lower position vandthu: prevents any movement resulting from vibratior or resulting from the action of gravity. However, the detent 24 is cammed out of the Wa: when the breech block is positively moved upward by the actuating lever I8.

It will be observed that the detent 2 4, engage: the block il in such a way that it resists upwarc movement thereof, without however interfering with free downward movement of the block wher the stop t!) is moved out of the way to release the block.

It should be quite apparent from the. foregoing and reference to the drawing that thepdetent 24 is so located as not only to prevent upward accidental movement of the breech block by gravitationor as lthe result of vibration; but.'V also kprovides for ready removal of the breech blocl-{foi inspection or replacement. This is due' to, Vthe fact that the detent 'M projects from the leg Ilt of the barrel extension in position toerigage the top edge of the breech block. Hence, when Ythe stop 20 is moved on its pivot 202' tothe dot-anddash line position of Fig. 1, the breech block may freely slide or drop out because there is nopositive locking engagement of the detent with .the breech block as in prior constructions of which I amI aware and wherein the detents enter kthe breech blocks adjacent their lower ends.v Under my invention, the detent. 24 engages with or projects across the top edge ofthe breech block when thebottom of the breech block is resting 'flatly on the stop 2|) to locate and maintain the T-slot il in accurate alignment to receive the studs I8lu as they approach the breechblock to engagein the T-slot |'|a to effect raising and loweringvof the breech block in accordance with the functioning of the gun. y l

Inl actual practice I have found that my construction and arrangement of means for supporting and stabilizing the breech block far surpasses' any means heretofore provided, of which Iavm` aware. This is due to the fact that the detent extends laterally through one of the legs ofthel barrel extension and is so located relative tothe accidental upward movement` due either tol vibration or gravitation resulting from vthe position of the mount.l Said means holds the breech block in said position in a manner greatly superior to any that has heretofore been possible by prior means since the latter resulted in disturbing the-location of T-slot |18 with respect to the studs I8b for free and unobstructed entrance of the studs into said channel.

In the foregoing specification and the following claims, a number of descriptive terms have been used such as upwardj downward, vertical, top, and the like. A11 of said terms are used in a relative sense with relation to the position of the rearm shown in the drawing when the same are held in a vertical position. Said terms are to be considered in the same relative sense regardless of the position in which the gun may be disposed.

What I claim is:

1. In an automatic rearm, the combination of a casing, a longitudinally reciprocable barrel,

a barrel extension connected with the barrel and positioned within the casing, a breech block guided on the barrel extension for downward and upward movement out of and into breeech closing position, mechanism adapted to engage the breech block for moving the same downward and upward in timed relation with the reciprocation of the barrel and barrel extension, a stop carried by the barrel extension and having a face adapted to engage the lower end of the breech block for limiting downward movement thereof and properly positioning the same for engagement by said mechanism, the said stop being movable out of its normal position so as to permit free downward movement of the breech block from the barrel extension, and a spring-pressed detent extending transversely through the barrel extension in a direction substantially normal to the longitudinal axis of the barrel and positioned to engage one side of the top of the breech block when its lower end is in engagement with said stop so as to resist upward movement of the breech block away from said stop and permit free downward movement of the breech block when said stop is moved out of its normal position, said detent also permitting the breech block to properly seat itself against said face of said stop when the stop is in its normal position.

2. In an automatic fire arm, the combination of a casing, a longitudinally reciprocable barrel, a barrel extension connected with the barrel and positioned within the casing, a breech block guided on the barrel extension for downward and upward movement out of and into breech closing position, mechanism adapted to engage the breech block for moving the same downward and upward in timed relation with the reciprocation of the barrel and barrel extension, a stop carried by the barrel extension and having a face adapted to engage the lower end of the breech block for limiting downward movement thereof and properly positioning the same for engagement by said mechanism, the said stop being movable out of its normal position so as to permit free downward movement of the breech block from the barrel extension, a springpressed detent extending transversely through the barrel extension in a direction substantially normal to the longitudinai axis of the barrel and positioned to engage one side of the top of the breech block when its lower end is in engagement with said stop so as to resist upward movement of the breech block away from said stop and permit free downward movement of the breech block when said stop is moved out of its normal position, said detent also permitting the breech block to properly seat itseli against said face of said stop when the stop is in its normal position, and cooperative means disposed on said detent and barrel extension for limiting the movement of the detent in breech block engaging direction.

WILLIAM L. svi/ARTZ.

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