US3270456A

US3270456A - Breech-bolt mechanism for bolt-action firearms

Info

Publication number: US3270456A
Application number: US484213A
Authority: US
Inventors: Carl H Benson
Original assignee: OF Mossberg and Sons Inc
Current assignee: OF Mossberg and Sons Inc
Priority date: 1964-12-17
Filing date: 1965-09-01
Publication date: 1966-09-06
Anticipated expiration: 1983-09-06

Description

Sept. 6, 1966 c. H. BENSON 3,270,456

BREECH-BOLT MECHANISM FOR BOLT-ACTION FIREARMS Original Filed Dec, 17, 1964 "'l 72 JP3@ 4, 4e 68 l 22 5 g4 ,8

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4o v 1 :IHI 3o 8 '4 z8 31 60 sa 98 u /blg l 96 52 /vlg4 3,270,456 BREEcH-BoLT MECHANISM .non BOLT-ACTION FIREARMS u Carl H. Benson, New Haven, Conn., assigner to 0. F.

This invention relates to firearms, and it relates more particularly to bolt-action firearms having an improved breech-bolt mechanism, this application being a division of my copending application, Ser. No. 419,061 led December 17, 1964, now Patent No. 3,234,679.

In some bolt-action firearms the handle of the breechbolt must be drawn out the back en-d of the receiver in order to reload the gun. With'guns of this general design, the breech-bolt slides in and out of the rear end of the receiver which is open at this end, and a bolt-latch is provided to stop the bolt at its rearmost limit of travel so that it does not accidentally come completely out of the receiver. The bolt-latch however is releasible in order to permit the bolt to be withdrawn through the rear end of the receiver when disassembling the'gun. As the bolt is returned to its breech-closing position, the bolt handle must be aligned with a longitudinal slot in the receiver, through which it slides before being swung' down into bolt-locking position in a transverse locking slot.

An object of the present invention is to provide a mechanically simple means for maintaining alignment of the bolt handle with the longitudinal slot in the receiver. Another object of the invention is to reduce the length of the receiver in comparison with the length of the stroke of the breech-bolt, thereby reducing the amount of material in 'the receiver. A further object of the invention is to provide a suitable bolt-latch for positively stopping the rearward travel of the bolt which, however, may be readily removed from the receiver -by simply depressing the trigger.

These and other objects and advantages of the invention4 will be more apparent from the following detailed description of a breech-bolt mechanism embodying the invention as shown in the accompanying drawings by way of example.

In the drawings:

FIG. 1 is a longitudinal vertical section of the rear portion of the receiver of a bolt-action firearm in which the invention is employed;

FIG. 2 is a top plan view of the rear of the receiver with the receiver and bolt partially broken away in order to expose certain parts;

FIG. 3 is a view similar to FIG. 1, but showing the bolt and trigger-plate in full elevation, with the bolt in its fully retracted position; and

FIG. 4 is a view of the underside of the rear portion of .the bolt taken on the line 4-4 of FIG. 3, portions being broken away.

The firearm shown in the drawings includes a receiver 10, which is suitably mounted in a full stock 14 by means of a take-down bolt (not shown) located just in front of a box-type magazine 16. A breech-bolt 18 is reciprocally guided within receiver for movement into and out of breech-closing position. The exposed rear end 19 of bolt 18 is streamlined with the receiver and stock, giving the gun the general appearance of'a so-called hammerless firearm. Breech-bolt 18 consists of a forward, non-rotatable portion 20 and a rear portion 22 mounted so as to be rotated relative to the forward portion 20 by means of a bolt-handle 24 (FIGS. 2 and 3), rigidly fixed to the rear portion 22. To this end, the forward portion 20 of the United States Patent O.

3,270,456 Patented Sept. 6, 1966 bolt is provided with a cylindrical boss 21, on which the rear portion 22 is journaled. A key .23, fitting within a circumferential groove 25 on boss 21, prevents

portions

20 and 22 from separating longitudinally while permitting rotational movement of the rear portion 22 relative to the forward portion' 20. Reciprocation of bolt 18 is effected in a conventional manner by bolt-handle 24, which may be swung about the longitudinal axis of the bolt into and out of locking relation with a transverse 4slot 26 in the receiver. Bolt 18 'can thus be retracted to the position shown in FIG. 3 for ejecting an empty cartridge and reloading in the usual manner Iby raising bolt-handle- 24 out of transverse slot 26 into a longitudinal slot 27, and then by withdrawing the bolt rearwardly.

The trigger mechanism indicated generally at 28 is supported in a hollow trigger-plate 30 securely fastened to the underside of receiver 10 within a hollowed-out portion of stock 14. lIn this instance trigger-plate 30, including the trigger guard 32, is formed as an integrally molded unit of synthetic material, such as nylon. The upper part of trigger-plate 30 opens toward, and is rigidly connected to, the underside of receiver 10 by means of a mounting screw 35 at its front end and a cross pin 36 spaced rearwardly thereof. Receiver 10 and trigger-plate 30 comprise the frame for the firing and trigger mechanisms. Between transversely spaced side plates 37 of trigger-plate 30 are pivoted a trigger 38 and a sear 39 superimposed above the trigger. A nose portion 40 of the trigger extends forwardly and upwardly into operative engagement with sear 39 and is provided on its upper surfa'ce with a tooth 42 for engagement in a seat-notch 44 in a depending portion 46 of sear 39 adapted to engage and press downwardly against the tooth 42 -on thetrigger when the action is cocked.

A cocking lug 48 on the upper side of sear 39 projects upwardly through a narrow longitudinally extending slot 50 in the underside of receiver 10 into the path of a cocking stud S2 which extends down through an opening 54 (FlG. l) in the bottom of bolt 18 from a spring-loaded striker 56 therein. Striker 56 -is.permitted limited movement longitudinally within a cylindrical chamber inside bolt 18 under the const-ant pressure of striker spring 57.

ice

Trigger 38 is urged counter-clockwise, as shown in FIG. 1,

ment with sea-r 39, which in turn is pivoted on cross pin 36. As hereinbefore mentioned, pin 36 also helps mount trigger-plate 30 to the underside of receiver 10 by passing through a pair of spaced depending tabs 62 on opposite sides of slot 50 in receiver 10 and through upstanding -portions 64 (FIG. 3) at the upper edges of sidewalls 37 of trigger-plate 30, between which tabs 62 are closely received. Pin 36 may be secured in place by av spring washer 66 (FIG. 3) adjacent the outer surface of triggerplate 30. Sear 39 is also urged in a counter-clockwise direction as shown -in the drawings by means of a sear spring 68 mounted in a socket in the inner surface of trigger-plate 30. It is apparent from FIG. 1 that the striker 56 will bereleased t-o fire the gun when trigger 38 is retracted in a clockwise direction dislodging its tooth 42 from the sear-notcli 44 of sear 39. Since the force of the striker spring 57 is many times greater than that of sear spring 68, sear 39 is pivoted clockwise by stud 52 immediately upon being unblocked by trigger 38 and the striker slams forward t-o fire a cartridge.

Extending rearwardly and upwardly from trigger 38 is a safety finger 72, the upper end of which is disposed adjacent the underside of the tail portion 19 of'bolt 18 for engagement with a safety lug 74 carried by bolt 18. Safety lug 74 is secured at .its upper end by means of an assembly screw 76 to a longitudinally slidable thumbpiece 78 located in an elongated groove 80 in the upper surface of tail portion 19 of bolt 18. An elongated slot J 82 is cut downwardly through bolt 18 centrally of groove 80 in order to accommodate the upper end of safety lug 74 and to guide it for movement with thumb-piece 78 on the bolt.

It will be noted that the upper surface of the tail portion of bolt 18 slopes rearwardly in order to continue uninterruptedly the smooth contour defined by the bolt in the upper surface of the stock where the thumb of the shooters hand is lpositioned when firing. When the thumbpiece 78 and safety lug 74 are located in their rearward or safety-on position as shown in FIG. l, trigger 38 is blocked against pivotal movement in a clockwise direction by engagement of its safety finger 72 with a stopsurface 79 at the lower end of safety lug 74. However, when thumb-piece 78 is slid forward and up until stopsurface 79 is clear of finger 72, trigger 38 is free to pivot clockwise enough to disengage sear 39, thereby releasing striker 56. Accordingly when thumb-piece 78 is forward, the safety is off or in firing position while, with the thumb-piece moved back so that safety lug 74 locks safety finger 72, as shown in FIG. 1, the safety is on and the gun is safe.

In order to cock striker 56, the leading edge 92 of opening 54 (FIGS. 3 and 4) in bolt 18 is sloped forwardly so as to cam cooking stud 52 back against the striker spring 57 when the rear portion 22 of bolt 18 is pivoted about its axis upon lifting bolt-handle 54 out of locking position in transverse slot 26 4of receiver 10. Striker 56 carries a firing pin 94, which is fixed thereto and is guided within a longitudinal passage through the forward portion 20 of bolt 18. It will be noted that the lower end of cocking stud 52 extends down into the elongated slot 50 in the bottom of receiver 10 and, therefore, that it is prevented by the walls of slot 50 from moving laterally about the longitudinal axis of the receiver and bolt when the rear portion 22 of bolt 18 is pivoted to unlock the breech. Consequently, upon unlocking bolt 18, rotation of its rear portion 22 causes opening 54 in the bolt to move transversely of cocking stud 52, thereby bringing its cam surface 92 into operative engagement with stud 52 in order to cock striker 56.

As best seen in FIG. 4, opening 54 in bolt 18 is also provided with a narrow latch-portion 96, both sides of which extend circumferentially of the bolt, the forward edge thereof being notched slightly at 98 in order to provide a retaining seat for cocking stud 52 in its fully retracted position. Striker 56 is thus positively latched in its cocked position as the bolt is manipulated during the usual extraction, ejection and loading operations. Accordingly, as the bolt-handle 24 is uncocked, the striker 56 is simultaneously retracted by cam 92 into a cocked position with its cocking stud 52 resting in the detent 98 where it is retained while the bolt is retracted in reloading. When bolt 18 is moved forward again into breechclosing lposition, cocking stud 52 engages the upstanding cocking lug 48 of sear 39, which then retains the striker in its cocked position as the rear portion 22 of bolt 18 is rocked back into its bolt-locking position. As the rear of the bolt is rotated into bolt-locking position, the opening S4 moves relative to the cocked stud 52 of the striker 56, so that the `latch-portion 96 thereof is no longer in registery with stud 52. At this point stud 52 lies adjacent the rear edge of opening 54 at the widest part thereof so that stud 52 has adequate room to m'ove the full forward travel of striker 56 in order to re the cartridge.

Rotation of the forward part 20 of the bolt 18 is prevented by cartridge extractor claws 100 (FIG. 3), which project laterally from the breech-end of the bolt into longitudinal grooves 102 in the inner sidewalls of receiver 10. In addition a cartridge case ejector 104 (FIG. 2) is mounted on the receiver opposite the ejection port 106 thereof, such ejector being fastened to the outer side of the receiver and having an ejector finger 108, which extends through an opening in the receiver into a longitudinal groove 110 in the side of the forward portion 20 of the bolt. Groove extends forwardly to the breech end of the bolt so that when the bolt is fully retracted ejector finger 108 projects beyond the face of the bolt to engage the empty cartridge case and eject it from the receiver in the usual manner.

It will be noted that the present construction permits the receiver to be shortened substantially at its rear end without adverse effect, thereby reducing manufacturing costs. As in most bolt-action guns, the bolt-handle 24 moves entirely out of the receiver when the bolt is fully retracted (FIG. 3). In order to prevent undesired rotation of the rear portion 22 of the bolt with respect to the forward portion while the bolt is thus retracted, a springloaded detent pin 112 (FIGS. 2 and 4) is provided at the front end of portion 22 near its periphery. Detent 112 is located circumferentially of the bolt such that upon rotation of the rear portion 22 out of breech-locking position, detent 112 becomes aligned with ejector groove 110 in the forward portion 20 of the bolt so that the end of its pin becomes engaged within said groove as shown in FIG. 4. Consequently, when the bolt is retracted to the position shown in FIG. 3, detent pin 112 prevents rotation of the rear portion of the bolt with respect to the forward portion. Bolt-handle 24 therefore is properly aligned with the longitudinal slot 2'/ in the top of receiver 10 when the bolt is returned to its breech-closing position. As bolt 18 approaches its forward limit of travel, detent 112 engages the rear edge of ejector finger 108 andis forced rearwardly out of groove 110 to allow the rear portion 22 of the bolt to rotate back into bolt-locking position as shown in FIG. 2. It should be noted, therefore, that ejector 104 performs a dual function in both ejecting cartridges and depressing the bolt-aligning detent 112.

When bolt 18 is closed, it is desirable to lock it with the receiver on both sides, in order to balance the forces of recoil when the gun is fired. Thus, as may be seen in FIG. 2, bolt-handle 24 locks within transverse slot 26 on one side of the receiver and in addition, a locking lug 114 on the opposite side of bolt 18 engages within a circumferentially extending groove 116 on the inner surface of receiver 10. In this instance, locking lug 114 consists of an extension of bolt-handle 24 which passes completely through the bolt and projects a short distance beyond the surface of the bolt on the opposite side. A longitudinal groove in the bottom of receiver 10 extends from the circumferential groove 116 rearward to the open end of the receiver. This permits both the locking lug 114 of bolt 18 and the cocking stud 52 of striker 454S to pass freely out the rear end of the receiver so that the bolt can be retracted after it has been unlocked.

Rearward travel of bolt 18 is normally limited by engagement of the cooking lug 48 of sear 39 with an endwall 118 of a groove 120 (FIG. 3) in the underside of the forward portion 20 of the bolt, into which locking lug 48 is urged by sear spring 68. The depth of groove 120 diminishes from its endwall 118 rearwardly until it blends smoothly with the peripheral surface of the bolt so that cocking lug 48 does not interfere with the return of the bolt to its breech-closing position. In order to remove the bolt entirely from the receiver for cleaning, it is only necessary to retract it in the usual manner to the position shown in FIG. 3, and to free bolt 18 by pulling on trigger 38 as if to fire the gun in order to withdraw cooking lug 48 downward out of groove 120. Bolt 18 can then slide freely out the open rear end of receiver 10. Withdrawal of cocking lug 48 is effected through engagement of a shoulder 122 on the upper edge of safety finger 7.2 of the trigger with a tail 124 at the back end of sear 39.

It will be understood that various changes and modifications may be made in the embodiment of the invention herein described without departing from the intended scope of the claims which follow.

What is claimed is:

1. A bolt-action firearm having a receiver and an elongated breech-bolt supported in said receiver for reciprocal movement longitudinally into and out of breech-closing position, said breech-bolt comprising a forward portionconfined to longitudinal movement and a rear portion rotatably connected to said forward portion for limited rotation relative thereto into and out of bolt-locking position, a bolt-handle fixedly mounted on said Irear portion, said receiver having a longitudinal slot through Which said bolt-handle passes when the breech-bolt is reciprocated longitudinally, a locking slot in said receiver disposed transversely of and opening into said longitudinal slot at its forward end to receive said bolt-handle when said rear bolt-portion is rotated into bolt-locking position, said longitudinal slot being opened at the rear end of the receiver such that said bolt-handle may travel rearwardly thereof when the breech-bolt is retracted, said longitudinal slot being shorter than the full rearward stroke of said breech-bolt, spring detent means interconnecting said forward and rear bolt-portions for preventing rotation of said rear portion when said breech-bolt is retracted in order to maintain alignment of said bolt-handle with said longitudinal slot in the receiver, the forward portion of said breech-bolt having a groove disposed longitudinally thereof and opening at the rear end of said forward boltportion, and a finger member mounted on said receiver and extending inwardly into said groove, said spring detent means being disposed in said rear bolt-portion for engagement in the end of said groove when said breechbolt is unlocked and said linger member being disposed relative to said spring-detent means such that movement of said breech-bolt into breech-closing position causes said linger member to be engaged by said spring-detent means in order to release said rear bolt-portion for rotation relative to said forward bolt-portion.

2. The combination defined in claim 1, which further includes a cartridge ejector mounted on said receiver, a portion of said ejector comprising said linger member, said groove also being open at the front end of said forward bolt-portion for projection of said ejector forwardly thereof in order to eject a cartridge.

3. In a bolt-action firearm having a receiver and an elongated breech-bolt supported in said receiver for reciprocal movement longitudinally into and out of breech-closing position, wherein said breech-bolt comprises a forward portion confined to rectilinear movement longitudinally of said breech-bolt and a rear portion rotatably connected to said forward portion for rotation relative thereto into and out of bolt-locking position, the combination therewith of a cartridge ejector mounted on said receiver and having a linger member extending inwardly into cooperative relation with said breech-bolt, the forward portion of said breech-bolt having an ejector groove in its periphery disposed longitudinally thereof in which said linger member rides as said breech-bolt is reciprocated, said ejector groove being open at both ends of said forward bolt-portion, and spring-detent means disposed in said rear bolt-portion 'for cooperative engagement with the rear end of said ejector groove when said rear bolt-portion is rotated out of its bolt-locking position in order to releasably restrain said rear bolt-portion against rotation relative to said forward bolt-portion, said ejector linger member being disposed relative to said spring-detent means such that movement of said breechbolt into breech-closing position causes said linger member to be engaged by said spring-detent means in order to release said rear bolt-portion for rotation relative to said forward bolt-portion.

References Cited by the Examiner UNITED STATES PATENTS 1,294,452 2/1919 Hammond 42-16 1,707,538 4/ 1929 Page 42-16 2,274,195 2/ 1942 Garrison 42--16 2,490,922 12/ 1949 Rutherford et al u 42-16 FOREIGN PATENTS 207,3 60 2/ 1940 Switzerland.

BENJAMIN A. BORCHELT, Primary Examiner.

Claims

1. A BOLT-ACTION FIREARM HAVING A RECEIVER AND AN ELONGATED BREECH-BOLT SUPPORTED IN SAID RECEIVER FOR RECIPROCAL MOVEMENT LONGITUDINALLY INTO AND OUT OF BREECH-CLOSING POSITION, SAID BREECH-BOLT COMPRISING A FORWARD PORTION CONFINED TO LONGITUDINAL MOVEMENT AND A REAR PORTION ROTATABLY CONNECTED TO SAID FORWARD PORTION FOR LIMITED ROTATION RELATIVE THERETO INTO AND OUT OF BOLT-LOCKING POSITION, A BOLT-HANDLE FIXEDLY MOUNTED ON SAID REAR PORTION, SAID RECEIVER HAVING A LONGITUDINAL SLOT THROUGH WHICH SAID BOLT-HANDLE PASSES WHEN THE BREECH-BOLT IS RECIPROCATED LONGITUDINALLY, A LOCKING SLOT IN SAID RECEIVER DISPOSED TRANSVERSELY OF AND OPENING INTO SAID LONGITUDINAL SLOT AT ITS FORWARD END TO RECEIVE SAID BOLT-HANDLE WHEN SAID REAR BOLT-PORTION IS ROTATED INTO BOLT-LOCKING POSITION, SAID LONGITUDINAL SLOT BEING OPENED AT THE REAR END OF THE RECEIVER SUCH THAT SAID BOLT-HANDLE MAY TRAVEL REARWARDLY THEREOF WHEN THE BREECH-BOLT IS RETRACTED, SAID LONGITUDINAL SLOT BEING SHORTER THAN THE FULL REARWARD STROKE OF SAID BREECH-BOLT, SPRING DETENT MEANS INTERCONNECTING SAID FORWARD AND REAR BOLT-PORTIONS, FOR PREVENTING ROTATION OF SAID REAR PORTION WHEN SAID BREECH-BOLT IS RETRACTED IN ORDER TO MAINTAIN ALIGNMENT OF SAID BOLT-HANDLE WITH SAID LONGITUDINAL SLOT IN THE RECEIVER, THE FORWARD PORTION OF SAID BREECH-BOLT HAVING A GROOVE DISPOSED LONGITUDINALLY THEREOF AND OPENING AT THE REAR END OF SAID FORWARD BOLTPORTION, AND A FINGER MEMBER MOUNTED ON SAID RECEIVER AND EXTENDING INWARDLY INTO SAID GROOVE, SAID SPRING DETENT MEANS BEING DISPOSED IN SAID REAR BOLT-PORTION FOR ENGAGEMENT IN THE END OF SAID GROOVE WHEN SAID BREECHBOLT IS UNLOCKED AND SAID FINGER MEMBER BEING DISPOSED RELATIVE TO SAID SPRING-DETENT MEANS SUCH THAT MOVEMENT OF SAID BREECH-BOLT INTO BREECH-CLOSING POSITION CAUSES SAID FINGER MEMBER TO BE ENGAGED BY SAID SPRING-DETENT MEANS IN ORDER TO RELEASE SAID REAR BOLT-PORTION FOR ROTATION RELATIVE TO SAID FORWARD BOLT-PORTION.