US2487621A - Breech mechanism for automatic firearms - Google Patents

Description

Nov. 8, 1949 G. WEBB ETAL BREECH MECHANISM FOR AUTOMATIC FIREARMS Filed Nov. 9, 1945 550x55 Webb 22L SWEF'E J'F'zvanbars WIYZIE .M flttarng 'nections.

Patented Nov. 8, 1949 BREECH MECHANISM FOR AUTOMATIC FIREARMS George Webb, Hartford, Conn., and William L.

Swartz, Miami, Fla., assignors to Colts Manufacturing Company, a corporation of Connecticut Application November 9, 1945, Serial N 0. 627,627

8 Claims.

The invention relates particularly to a breech mechanism for a firearm of the type wherein the barrel and the breech structure are permitted to reciprocate bodily as a unit during recoil and counter-recoil, the feeding mechanism in its entirety remaining stationary during such reciprocation. A firearm of the type referred to is disclosed in the patents to Marc Birkigt, Nos. 2,159,- 126, 2,159,127, 2,199,871 and 2,199,872.

With a firearm of the type referred to, the breech bolt is longitudinally reciprocable in the 'breech casing and there is a releasable locking mechanism for holding the bolt in its forward breeched position. For releasing the locking mechanism and for applying force to move the bolt rearward, there is provided a push rod, or preferably two push rods, movable rearwardly upon firing. Heretofore these push rods have been actuated by a gas operated means receiving gases of explosion from the barrel, the said gases reacting upon a piston which in turn moved the push rods by means of suitable mechanical con- The gas operated mechanism has been frequently found objectionable on account of clogging of the gas passages, or on account of sticking of the piston with resultant delayed action, or for other reasons. Furthermore, with a gas operated mechanism the rate of rearward movement of the push rods has no fixed or determined relationship to the rate of rearward recoil movement of the barrel and casing.

The principal object of the present invention is to eliminate the gas operated mechanism with its inherent objections, and to provide for the same purpose a simple and positively acting mechanical device, which will reliably actuate the release mechanism for the lock and also move the bolt rearward Whenever recoil movement occurs.

A further object of the invention is to insure movement of the push rods in definitely timed relationship with the rearward recoil movement of the barrel and easing.

A still further object of the invention is to provide a gradually accelerated rate of rearward movement of the push rods, such gradually ac celerated movement being in definitely timed relationship with the rearward recoil movement of the barrel and easing.

Other objects of the invention will be apparent from the accompanying drawing and from the following specification and claims.

Of the drawing:

Fig. 1 is a side view of a firearm embodying the invention, the feed mechanism being omitted and. certain portions of the firearm being broken away with other portions shown in section along the line I-l of Fig. 2.

Fig. 2 is a plan view of the firearm shown in Fig. 1 with certain portions shown in section along the line 2--2 of Fig. 1.

Fig. 3 is an enlarged fragmentary view similar to Fig. 1 but showing the parts in different relative positions,

Fig. 4 is a front view of the lock release mechanism to which the invention particularly relates, the casing being omitted and the barrel being shown in dot-and-dash lines.

Fig. 5 is a vertical sectional view taken along the line 5--5 of Fig. 4.

Fig. 6 is a vertical sectional view taken along the line 66 of Fig. 4.

Fig. 7 is a view similar to Fig. 5 but showing an alternative construction.

Referring to the drawing, II and I2 represent respectively the barrel and the breech casing of a firearm of the type to which the invention is particularly applicable. In use, the firearm is so mounted that the barrel and the breech casing can reciprocate longitudinally as an entirety when firing occurs.

Carried by the casing I2 and in slidable engagement therewith is a slide member l3 which is adapted to carry a suitable feed mechanism or magazine, not shown. By means to be described, the slide member I3 is held stationary notwithstanding reciprocation of the barrel and casing. The feed mechanism is detachably connected with the slide I3, having a portion adapted to be engaged under a hook I4 and having another portion adapted to be engaged by a latch l5 controlled by a lever IB.

Positioned within the casing I2 is a breech bolt I! which is longitudinally reciprocable relatively to the casing. A releasable lock is provided for holding the bolt I! in its forward breeched position and, as shown, this look includes a strut I8 pivotally engaged at its forward end with the bolt and seated at its rear end in a notch in a transverse member I9 carried by the casing. Positioned at opposite sides of the breech bolt I1 and guided for longitudinal movement separate therefrom are two unlocking plates 20, 2E]. The plates 20, 20 are tied together by a cross member 2| which extends through a slot 22 in the bolt I I, the width of the slot being greater than the width of the cross member. Each plate 20 has a notch 23 having a rearward facing cam surface, and the strut l8 has upward projecting hooks 24 projecting into the notches 23 and having forward facing cam surfaces adapted to engage with the rearward cam surfaces of the notches. When the plates are in their forward positions as shown in Figs. 1 and 2, the rear end of the strut i8 is seated in the notch in the transverse member l9 and the bolt l! is locked in its forward breeched position, The cross member 2| is at the front of the slot 22. However, when the plates are moved rearward relatively to the breech bolt, the before-mentioned cam surfaces engage eah other with the result that the strut 18 is swung upward to the position Shown in Fig. 3, being thus removed from the notch and being free to mpye rearward over the top of the member l9. The bolt I1 is thus unlocked and move rearifiard upon recoil. Rearward movement of the plates 2|], 20 with respect to the bolt I] is limited by engagement of the cross member 2! with the rear of the slot 22. Upon counter-recoil the bolt returns to its forward breeched position and the strut I3 returns to the locking position as shown in Fig. 1.

For moving the plates 26, 20 there are provided two push rods 25, 25 which are carried by the casing and which are longitudinally movable relatively thereto. Each push rod abuts at its rear against the front or the corresponding unlocking plate 20. It will be observed that the push rods 25, 25 serve not only to eifect unlockii'ig as described, but also serve after the plates 20 have reached their limit of rearward relative movement to apply pressure to the bolt to insure its rapid rearward movement in the breech casin l2. The mechanism as thus fardescribedis old in the art and does not of itself constitute any part of the present invention. Two separate plates 20, 20 and two separate push rods 25, 25 are commonly used and are preferred, but the inventionis not necessarily so limited. However, the novel mechanism to be now described is adapted for use with two push rods; and this is the mechanism preferred.

It has already been stated that the barrel and the breech casing are longitudinally reciprocable upon firing, and that the slide member [3 is held stationary notwithstanding the reciprocatory movement of the barrel and casing. In accordance with the present invention, the relative movement of the casing with respect to the slide member upon firing is utilized to move the push rods longitudinally so as to effect the release of the lock. When two transversely spaced push rods 25, 25 are provided as is preferred, there are provided two transversely spaced levers Z6, 26 each having between its ends a pivot aperture for receiving a transverse pivot pin 21 carri d by the reciprocable casing l2 and each engaging at 28 near its lower end with the corresponding push rod Each lever 26 has a slot 29 near its u per end for receiving a stationary pivot pin 30 carried by or connected with the station iit slide l3. The result is that when the casing l2 moves rearward during recoil the pivotal connection at 21 moves rearward, and inasmuch as the pivotal connection at 30 is stationary the levers 26, 23 move in the clockwise direction about the piv} otal axis at 21 and serve to push the rods 25, 25 toward the rear to effect unlocking as shown in Fig. 3. When the casing moves forward at; counter-recoil, the levers 25, 28 are restored to the positions shown in Fig. 1 and the push rods 25, 25 are free to move forward to the 'ptsitiah 7 shown in that figure.

It Will be seen that in View Of the dsbiibd mechanical actuating means for the push rods, the said rods are moved in definite predetermined timed relationship with the recoil movement of the barrel and casing. Thus the unlocking and the initial movement of the bolt are effected in timed relation to the recoil movement.

A lug or projection 3l extends upward from the top of the casing at the front end thereof and a bracket 32 is secured to the forward face of this lug, the said bracket carrying the pivot pin 21; Two forward extending brackets 33, 33 are secured by cap screws 34, 34 to the slide 3 at opposite sides thereof, these brackets near their forward ends carrying the transverse pivot pin 30. Preferably; the brackets 33, 33 are utilized for maintaining the slide I3 stationary. To this end the brackets are provided respectively with laterally projecting lugs 35, 33 which are engaged by longitudinally extending tie rods 38, 3B, the forward ends of which are secured to a stationary portion of the mount for the firearm.

In order to hold the pivot pin 30 securely in place and to assist the brackets 33, 33 in preventing relative upward movement thereof, the said pin carries a roller 31. A bracket 33 is seciired to the rear face of the lug 3| and this bracket has "a portion which extends forward and is immediately above the roller 37. It will be seen that the bracket 38 moveswith the casing and therefore moves relatively to the roller 31, the axis 'of which is stationary. The roller engagiii'g face of the bracket 38 is horizontal and the bracket therefore serves to prevent upward movement of the roller .and thus serves to more securely held the pivot pin 30.

Preferably and as shown, the bracket 32 carries a threaded stud '39 which projects rearward through a central opening in the lug 3i and into an opening in the lower rear portion of the bracket 38. Keys 40 prevent the bracket 32 from turning about the axis of the stud. A nut t] engages the rear portion of the stud and alsti the bracket 38, the'stud and nut thus servra to hold mpia e both of the brackets 32 and 3B. The bracket 32 is shown as having an integrai flange 42 which extends along one side of the lifg 3|, and is provided With a hole 43. This bracket has no function for the o eration of the rods, but serves to carry a member, not shown,,for ope'ratihg the feed mechanism.

In Fig. 7 there is shown an alternative constructioii wherein levers M are substituted for the ivers 26. Each lever in has a bearing aperture for receiving the pivot pin 30 and has a longitudinal slot for receiving the pivot pin 21. It will be seen that whenthe lever 44 moves from the position shown in Fig. 7, toa position corresponding to that shown in Fig. 3, there is a gradual reduction of the length of the lever arm represented by the distance between the pivot pins 30 and 21 and a gradual increase of the length of the lever arm representedby the distance between the pivot pin 2'! and the point of engagement at 23 with the push rod. This gradual change in the relationship between the lengths of the two lever arms causes a gradual acceleration of the rate of movement of the push T65. relative to the rate of movement or the barrel and easing. V V a Preferably each slot 45, while generally longitiidi nal; is at man-git to a line connecting the of thepin 21 the axis of the pin 30 is initially in the lower end of the S1017,

all as shown in Fig. 7, the upper part of the said slot being forward of the said line.

It will be seen that the inclined position of the slot 45 with the resultant forward position of the upper end thereof causes increased rearward movement of the lower end of the lever at 28 with corresponding increased rearward movement and increased acceleration of the corresponding push rod 25.

What is claimed is:

1. An automatic firearm comprising in combination, a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releas able lock for holding the bolt in its forward breeched position, means for releasing the lock including a push rod carried by the casing and longitudinally movable relatively thereto, a lever having between its ends a pivotal connection with the reciprocable casing and engaging near its lower end with the push rod, and means connected with the stationary slide member and having pivotal connection with the lever near its upper end whereby upon recoil movement of the casing the lever is moved about its first said pivotal connection to move the push rod and thereby release the lock.

2. An automatic firearm comprising in combination a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock including a push rod carried by the casing and longitudinally movable relatively thereto, a lever having between its ends a pivotal connection with the reciprocable casing and engaging near its lower end with the push rod, and means connected with the stationary slide member and having pivotal connection with the lever near its upper end whereby upon recoil movement of the casing the lever is moved about its first said pivotal connection to move the push rod and thereby release the lock, one of said pivotal connections to the lever being slidable upon recoil of the casing to increase as the casing recoils upon firing the ratio of the distance between said pivotal connection to the stationary slide member and the push rod engaging portion to the distance between said pivotal connection to the stationary slide member and the pivotal connection with the reciprocable casing.

3. An automatic firearm comprising in combination, a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock and for moving the breech bolt rearwardly, such means including a push rod carried by the casing and longitudinally movable relatively thereto, a lever having between its ends a fixed pivotal connection with the reciprocable casing and engaging near its lower end with the push rod, the said lever having a longitudinal slot in its upper end portion, and a stationary pivot pin connected with the stationary slide member and entering the said slot in the lever whereby upon recoil movement of the casing the lever is moved about its said pivotal connection to move the push rod and thereby release the lock.

4. An automatic firearm comprising in combination, a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock 7 and for moving the breech bolt rearwardly, such means including a push rod carried by the casing and longitudinally movable relatively thereto, a lever having a pivot aperture near its upper end and having a generally longitudinal slot between its ends and the said lever engaging near its lower end with the push rod, a pivot pin carried by the reciprocable casing and entering the slot in the lever, and a stationary pivot pin carried by the stationary slide member and entering the pivot aperture in the lever whereby upon recoil movement or" the casing the lever is moved about the movable pivotal connection formed by the first pivot pin and the slot to move the push rod at a rate gradually accelerated with respect to the rate of movement of the casing and barrel.

5. An automatic firearm comprising in combination, a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock and for moving the breech bolt rearwardly, such means including a push rod carried by the casing and longitudinally movable relatively thereto, a lever having a pivot aperture near its upper end and having a generally longitudinal slot between its ends and the said lever engaging near its lower end with the push rod, the said slot being inclined forwardly from a line extending through the pivot aperture and the lower end of the slot, a pivot pin carried by the reciprocable casing and entering the slot in the lever, and a stationary pivot pin carried by the stationary slide member and entering the pivot aperture in the lever whereby upon recoil movement of the casing the lever is moved about the movable pivotal connection formed by the first pivot pin and the slot to move the push rod at a rate gradually accelerated with respect to the rate of movement of the casing and barrel.

6. An automatic firearm comprising in combination, a breach casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with the casing, means for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock including two transversely spaced push rods carried by the casing and longitudinally movable relatively thereto, a projection on the reciprocable casing carrying a transverse pivot pin, two brack levers each having between its ends a pivot aperture receiving the first said pivot pin and each having in its upper end portion a slot receiving the second said pivot pin,- the said levers engaging near their lower ends with the respective push rods whereby the push rods are moved to release the lock upon recoil movement of the casing with resultant movement of the levers about the first said pivot pin.

'7. An automatic firearm comprising in combination, a breech casing and a barrel longitudinally reciprocable upon firing, a slide member having slidable engagement with s the casing, transversely spaced forward extending brackets on the slide, means engaging the brackets for holding the slide member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock including two transversely spaced push rods carried by the easing and longitudinall movable relatively thereto, a projection on the reciprocable casing carrying a transverse pivot pin, a transverse pivot pin above the first said pivot pin andcarried by the said brackets, and two transversely spaced levers each havin between its endsa pivot aperture receiving the first said pivot pin and each having in its upper end portion a slot receiving the second said pivot pin, the said levers engaging near their lower ends with the respective push rods whereby the push rods are moved to release the look upon recoil movement of the casing with resultant movement of the levers about the first said pivot pin.

8. An automatic firearm comprising in combi- 8 nation, a breech casing and a barrel longitudin'ally reciprocable 'upon firing, a slide member having slidable engagement with the casing, means, for holding the said member stationary notwithstanding reciprocation of the casing and barrel, a breech bolt in the casing and longitudinally reciprocable relatively thereto, a releasable lock for holding the bolt in its forward breeched position, means for releasing the lock including two transversely spaced push rods carried by the casing and longitudinally movable relatively thereto, a projection on the reciprocable casing carrying a transverse pivot pin, two brackets connected with the stationary slide member and carrying a transverse pivot pin above the first said pivot pin, two transversely spaced levers each having between its ends a pivot aperture receiving the first said pivot pin and each having in its upper end portion a slot receiving the second said pivot pin, the said levers engaging near their lower ends with the respective push rods whereby the push rods are moved to release the lock upon recoil movement of the cas ing with resultant movement of the levers about the first said pivot pin, a roller on the second said pivot pin, and a guide carried by the casing and positioned above the roller to engage it and prevent upward movement of the second said pivot pin.

GEORGE WEBB. WILLIAM L. SWARTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,637,? Von Kiraly et a1. Aug. 2, 1927 r 2,159,127 Birkigt May 23; 1939

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