US2146743A

US2146743A - Firearm

Info

Publication number: US2146743A
Application number: US183469A
Authority: US
Inventors: Jr Melvin M Johnson
Original assignee: EDWARD E RICE; MELVIN M JOHNSON; MELVIN M JOHNSON JR
Current assignee: EDWARD E RICE; MELVIN M JOHNSON; MELVIN M JOHNSON JR
Priority date: 1938-01-05
Filing date: 1938-01-05
Publication date: 1939-02-14
Anticipated expiration: 1956-02-14
Also published as: NL52759C; GB511365A; BE431675A; FR847565A

Description

Feb. 14, 1939. M. M. JOHNSON, JR

FIREARM Fi1edJan. 5, 1931s NNO.

UNITED STATES PATENT OFFICE FIREARM Melvin M. Johnson, Jr., Brookline, Mass., assignor to Melvin M, Johnson, Brookline, Mass., Ed-

ward E. Rice, Boston, Mass., and himself, as

trustees of Johnson Patent Trust Application January 5,

Claims.

In automatic firearms where the breech opens shortly after detonation much difficulty is encountered in extracting shells owing to the expansion of the shells in the firing chamber by in the initial stage of bolt recoil, serves to kickthe plunger to the rear as aforesaid, therebyto facilitate extraction. Thus the cam lug on the bolt constitutes an actuator which has a transverse (rotary) component of movement at the 1938, Serial No. 183,469

forward end of its reciprocation, and the plunger constitutes a kicker which recoils relatively to the bolt in response to said transverse component of movement.

position until the bolt returns to forward position, the barrel then being pushed to its forward position by the bolt after the lugs I5 on the bolt have passed through the spaces between the lugs 5 gas pressure. The object of the present inven- For the purpose of illustration a typical em- 6 tion is to overcome this dimculty. bodiment of the invention is shown in the accom- My invention is based on the principle that panying drawing in which, friction between sliding surfaces can best be over- Fig. 1 is a top plan view with parts broken come by an impact in contradistinction to a away and parts in section, showing the breech Steady force. For example if a shell sticks in a mechanism in closed position; l0 ring chamber it can be removed with a ramrod Fig. 2 is a similar view showing the parts in more easily by lightlytapping on the ramrod the positions which they occupy at the moment than by 'steadily pushing with a heavier force. extraction begins; According to-the present invention AI provide Fig. 3 is a similar view showing the parts in Al5 means for applying to the bolt, at the beginning' the positions which they occupy at the moment l5 of each extraction, a sharp blow to the rear, of ejection; and thereby to start the sliding movement of the Figs. 4 and 5 are sections on lines 4 4 and shell in the chamber. This is accomplished by 5-5 of Fig. 2. including, in fthe breech mechanism, a kicker 'I'he particular embodiment of the invention which recoils relatively to the bolt diuing the chosen for the purpose of illustration comprises 20 initial stage of recoil and which has a reara` receiver I, a barrel comprising two parts 2 and wardly-facing abutment for impact against a IlA threaded together at 4, a bolt 5, an extractor 6l forwardly-facing abutment on the bolt, the abutmounted on the bolt, an ejector 'i mounted in an A ments being spaced apart when the bolt is in opening 8 in the-side of the receiver, a handle 9 closed position and the spacing being correlated for manually retracting the bolt, the aforesaid 9 5 with the relative movement of said part and bolt plunger or kicker I0, a strut II pivotally conto cause the first abutment to impinge against nected to the rearward end of the plunger I0 byv the second abutment when extraction is to be pin I2, the strut Il extending back to the recoil initiated. The aforesaid part preferably comspring not shown, and a firing pin I3. The rear- Y prises a plunger interposed between the nolt and ward end o1' the barrel sleeve 3 has an annular 30 recoil spring which is kicked back in the initial row of inwardly projecting locking lugs I4 and recoil movement of the breech mechanism, prefthe forward end of the bolt has an annular row erably by a rotary component of the initial4 moveof outwardly projecting locking lugs I5. In the ment of the bolt. closing movement of the bolt the lugs I5 pass The invention is particularly applicable to flrebetween the lugs I4, after which the boli; is ro- 35 arms of tlie reciprocating barrel type in which tated in a counter-'clockwise direction (Figs. 4 the bolt has locking lugs seating against locking and 5) to bring the bolt lugs I5 in front of the abutments on` the barrel, a part of the bolt barrel lugs I4, thereby interlocking the bolt to (either the whole bolt or merely the bolt head) the barrel. When the gun is fired the bolt and. 40 having rotary or other transverse movement to barrel recoil together from the position shown in 40 bring the locking lugs into locking engagement Fig. 1 to the position shown in Fig. 2, and during with said abutments at the end of the closing this recoil the bolt is rotated, by mechanism movement of the bolt and out of locking engagehereinafter described, to bring the lugs I5 on the ment in the initial stage of the recoil movement bolt into alignment with the spaces between the of the bolt. In the preferred embodiment of the lugs I4 on the barrel, whereupon the bolt is free 45 invention the aforesaid plunger has a forwardlyto recoil. After the bolt is disengaged from the facing cam surface engaging arearwardly-facing barrel the latter may be returned to forward cam surface on a lug on the bolt which rotates position by a spring (not shown) as described the bolt into locked position at the forward end in my Patent No. 2,094,156, granted September o of the closing movement of the bolt and which, 28, 1937, or the barrel may remain in retracted I4 on the barrel, while the bolt is "rotating to f locked position during the final stage of its forward motion.

The rotary movement of the bolt to locked position is controlled by lugs I and I1 on the bolt 5 and plunger I0, respectively, the lug I1 having a forwardly-facing cam surface I8 engaging a rearwardly-facing cam surface I9 on the bolt lug I6 tending to rotate the bolt into locked position. Mounted on the lugs I6 and I'l are rollers 20 and 2l which fit into a groove in the top of the receiver (Figs. 4 and 5) to prevent rotation of the bolt and plunger during recoil. However, as shown in Fig. V5, the forward end of this groove has a lateral offset to permit rotation of the bolt to locked position at the forward end of its closing movement. To rotate the bolt out of locked position while the bolt and barrel recoil together, the lug I6 is provided with another cam surface 22 engaging a cam surface 23 which is fixed to the receiver. Thus, as the bolt recoils from .the position shown in Fig. 1 to the position shown in Fig. 2, the cam surfaces 22 and 2t rotate the bolt suiciently to bring the lugs I5 on the bolt into alignment with the spaces between the lugs on the receiver. Engagement of the roller 2B with the side of the aforesaid groove of the receiver stops the rotary movement and the bolt continues to the rear by straight-lined movement alone. In the particular embodiment of the invention shown in the drawingjthe cam surface 23 is formed on a lug 24 depending from a cover plate 25 which is mounted on the receiver by a dovetailed connection 26 (Fig. 5), the cover sliding into the receiver from front to rear and being held in position by a screw 21. The lug 24 seats to the rear against a shoulder 28 in the receiver so that the rearward thrust on the lug by the bolt lug I6 is transmitted directly to the receiver.

According to this invention, the bolt is provided with a forwardly-'facing shoulder 29 engageable by the rear end of the lug I'I to facilitate extraction. 'Ihis shoulder is spaced from the lug I6 on the bolt a distance slightly greater than the length of the lug I1 on the plunger so that at the moment the bolt is unlocked from the barrel (as illustrated in Fig. 2) there is sufficient space for back and forth movement of the lug I1 between the lug I6.and the shoulder 29. 'Ihis freedom of movement is utilized to facilitate extraction in the following manner: During the initial stage of recoil movement, while the bolt barrel and plunger are recoiling together and the bolt is rotating from locked to unlocked position, the plunger lug I'I is moving to the rear somewhat faster than the bolt because of the camming action between the surfaces I8 and IS on the lugs I6 and I1 respectively. Furthermore, at the moment the bolt is unlocked from the barrel its rearward component of movement is checked, through the medium of the extractor, by the tendency of the cartridge shell to stick in the firing chamber. Inasmuch as the plunger lug I1 is traveling faster than the bolt and is not checked by the cartridge, it continues to the rear,'impinging on Athe shoulder 29. By virtue of this rearward impact on the bolt at the moment extraction begins the shell is loosened in the firing chamber and the extraction is thereby facilitated. Y Immediately following this impact the bolt catches up with the plunger because of the resistance of the recoil spring acting on the plunger through the strut II and the bolt and plunger then continue to the rear to the position shown in Fig. 3 where the shell is ejected.

The body of the ejector 'I substantially fills the recess 8 in the side of the receiver and the forward end of the projector is provided with a narrow nn 30 on its inner face which engages the shell. The rear end of the ejector lies in a longitudinal groove 3l in the bolt, the forward end of the groove being gradually reduced in depth to'cam the ejector into the ejecting position shown in Fig. 3 as the bolt nears the end of its recoil movement.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modincations and equivalents which fall within the scope of the appendedy claims.

I claim:

1. A firearm comprising a bolt, an extractor on the bolt, and breech mechanism permitting automatic recoil of the bolt when the rearm is discharged, said mechanism including akicker which recoils relatively to the bolt before the bolt leaves the firing chamber and which has a rearwardly-facing abutment for engagement with a forwardly-facing abutment on the bolt, said abutments being spaced apart when the bolt is in closed position and the spacing being correlated with the relative movement of said part and bolt to cause the first abutment to impinge against the second abutment substantially when the bolt leaves the firing chamber thereby to facilitate extraction.

2. A iirearm comprising a bolt, an extractor on the bolt, a recoil spring, and breech mechanism normally locking the bolt in firing position and automatically unlocking the bolt when the vfirearm is discharged, said mechanism including a plunger interposed between the bolt and recoil spring which recoils relatively to the bolt during the initial stage of recoil and which has a rearwardly-facing abutment for engagement with a forwardly-facing abutment on the bolt, said abutments being spaced apart when the bolt is in closed position and the spacing being correlated with the relative movement of said plunger and bolt to cause the first abutment to impinge against the second abutment during said initial stage of recoil thereby to facilitate extraction.

3. A firearm comprising a reciprocating bolt having a rotary component of movement at the f forward end of its reciprocation, an extractor on the bolt, and automatic breech mechanism controlling the movement of the boltl said mechanism including a non-rotary kicker which recoils relatively to the bolt during the initial stage of recoil and which has a rearwardly-facing abutment" for engagement with a forwardly-facing abutment on the bolt, said abutments being vspaced apart when the bolt is in closed position and the spacing being correlated with the relative movement of said part and bolt to cause the rst abutment to impinge against the second abutment during said initial stage of recoil thereby to facilitate extraction.

4. A firearm comprising a reciprocating bolt, an extractor on the bolt, and breech mechanism permitting automatic recoil of the bolt when the rearm is discharged, said mechanism including an actuator reciprocating with the bolt and also having a transverse component of movement at the forward end of its reciprocation and said mechanism also including a kicker which recoils relatively to the bolt in response to said transverse component of movement and which has a rearwardly-facing abutment for engagement with a forwardly-facing abutment on the bolt, said abutments being spaced apart when the bolt is in closed position and the spacing being correlated with the relative movement of said bolt and kicker to cause the rst abutment to impinge against the second abutment during said initial stage of recoil thereby to facilitate extraction.

5. A firearm comprising a receiver, a recoiling barrel, locking abutments on the barrel, a reciprocating bolt having rotary movement at the forward end of its reciprocation, an extractor, locking lugs on the bolt for engagement with said abutments, a recoil spring, and a plunger between the bolt and spring, the bolt and plunger having cooperating cam surfaces for moving said lugs into locking engagement with said abutments by rotating the bolt at the forward end of its reciprocation, said receiver and bolt having cooperating cam surfaces for rotating the bolt while the bolt and barrel recoil together, thereby disengaging said lugs from said abutments and, through the medium of said first cam surfaces, kicking said plunger to the rear relatively to the bolt, the plunger having a rearwardly1facing surface impinging on a forwardly-facing surface of the bolt for facilitating extraction.

MELVIN M. JOHNSON, JR.