US2418946A

US2418946A - Breech bolt lock for firearms

Info

Publication number: US2418946A
Application number: US454961A
Authority: US
Inventors: Oliver H Loomis
Original assignee: Remington Arms Co LLC
Current assignee: Remington Arms Co LLC
Priority date: 1942-08-15
Filing date: 1942-08-15
Publication date: 1947-04-15
Anticipated expiration: 1964-04-15

Description

plrm l5, 1947. Q H Loglms 2,418,946

nmol! BOLT FOR FIREARIS Filed Aug. 15. 1942 3 Sheets-Sheet 1 w, 7- o. H. Looms Y BBEBCH BULT LOCK FOR FIRERNS Filed Aug. 15. 1942 3 Sheets-Sheet 2 AGEN s. m m H, o.

BREECH BOLT LOCK FOR FIREARMS Filed Aug. 15, 1942 3 Sheets-Sheet 3 l 4L .LJ

Patented Apr. 15, 1947 BREECH BOLT LCK FOR FIREARMS Oliver H. Loomis, Ilion, N. Y., assignor to Remington Arms Company, Inc., Bridgeport, Conn., a

corporation of Delaware Application August 15, 1942, Serial No. 454,961

4 Claims.

This invention relates to firearms, and, particularly to a firearm of the full recoiling barrel type in which the force of explosion drives the barrel breech block and related parts to the rear, and, in so doing, energizes devices which subsequently perform the functions of extraction, ej ection, cartridge feeding and breech closing required in automatic reloading.

An object of the invention is to provide a firearm having novel and improved features of construction. More specifically, it is an object to provide an automatic shotgun of improved shape and outline.

A further object is to provide a simplified construction having improved sighting and a relatively small receiver.

A further object is to reduce the friction between elements of the breech mechanism and the adjacent surfaces of the receiver.

A still further object is to provide improved construction to facilitate assembly and minimize the weight of the firearm.

Other objects, features and advantages will be apparent from the following description of one embodiment of the invention, the specific features and construction of which are illustrated in the accompanying drawings:

Fig. 1 is a right side elevation of the complete weapon with a portion of the stock in section.

Fig. 2 is a sectional view of the left side of the gun taken between lines 2--2 of Fig. 1 with the action closed.

Fig. 2a is an enlarged sectional view of the breech block assembly shown in Fig. 2. 1

Fig. 3 is a sectional view, similar to Fig. 2,?

but with the action open and showing the carrier latch `and dog mounted on the left side of the trigger plate.

Fig. 3a is a plan view of the assembled re control mechanism and trigger plate shown in Figs. 2 and 3.

Fig. 4 is a view similar to Fig. 3, but with the action further advanced.

. the recoil spring tube shown in Fig. 6.

Fig. 8 is a plan view of the carrier showing the carrier trunnions and the carrier locking and release means.

Fig. 9 is a fragmentary plan view on line 9-9 2 of Fig. 2a showing the operating handle connected to the action slide.

Fig. l0 is a fragmentary side elevation of the barrel extension showing the cartridge ejector.

Fig. 11 is a rear end view of the breech block and slide on line I I-l I of Fig. 2.

Fig. 12 is a plan View of the slide and slide link.

Fig. 13 is a right side elevation of the carrier link and dog assembly.

Fig. 14 is a fragmentary section of a modification of the breech bolt and barrel extension.

Onlyso much of the gun mechanism as is necessary for the illustration of the present invention has been shown and will be described. For a full description of a firearm, to which a particular embodiment of the invention illustrated is directly applicable, reference may be had to the patent to Browning, 659,507, October 9, 1900, or the patent to Loomis, 1,931,262, October 17, 1933.

A brief review of the general method of operation of the firearm may contribute towards a better understanding of the more detailed description to follow.

Referring to the drawings, when the gun is red, the forces of explosion drive the barrel, barrel extension and breech block assembly rearwardly. The breech block assembly, which includes an action slide, is locked to the barrel eX- tension by means of a locking block. The locked parts move to the rear against the resistance of the barrel restoring spring and breech bolt recoil spring until the rear end of the' bolt approaches the rear wall of the receiver, the locked parts then being urged to return to their original positions* by the aforesaid compressed springs. As .the locked parts begin their return movement, the action slide is arrested whereupon the breech bolt moves forward slightly relative thereto.

The relative movement of the bolt and slide unlocks the bolt from the barrel extension so as to permit the barrel and barrel extension to return to their closed positions, thereby extracting and ejecting the spent shell. The slide is then released by the unlocking of the cartridge carrier, which may be accomplished automatically by the feeding of a fresh shell onto the carrier from the magazine. As the slide and breech bolt return to breech closing position, the fresh shell which has been elevated by the carrieris pushed forwardly into the barrel chamber. The fire control mechanism functions in substantially the same way as described in the above mentioned patents, but includes some improvements hereinafter described in detail.

Receiver Referring specically to Figs. 1 and 2, the nrearm is shown provided with a receiver I5, the upper rear end of which has lbeen curved gradually downwardly and rearwardly as at I 6 so as to form a substantially continuous unbroken curve merging into the top surface of the butt sinck l1. thereby eliminating abrupt shoulders and effecting a pleasing streamlined appearance. Further, the line of sight along the receiver thus more nearly coincides with the top of the barrel I6, and, consequently, the groove I3 on top of the receiver adjacent the rear sight mount need not be cut as deeply as usual, thereby insuring a relatively strong construction.

The side and rear walls of the receiver are formed integrally with the upper portion thereof, the right hand side wall 20 having the usual shell ejecting opening 2l. The rear or end wall 22 of the receiver is substantially wedge shaped in section, as seen in Fig. 3, and formed with a substantially inverted U-shaped recess 23 open at -the bottom of the receiver, the recess being provided with an internal circumscribing flange 24 adjacent the rear portion of the end wall 22. 'I'he rear face 26 of the end wall 22 is recessed and has a shroud 21 formed as an integral part of the end wall of the receiver, the recessed portion and shroud forming a seat for the stock I1. To this end, the latter is reduced at its front end to form a neck 26 adapted to make a nice fit in the recess 26 and to provide a shoulder 29 adapted to aibut the shoulder of the shroud 21, the upper surface of the shroud and stock forming a smooth continuous curve downwardly to the small of the stock. v

Action spring assembly The stock I1 is secured to the rear wall of the receiver by the action spring assembly, which comprises axially aligned tubular members 35', 36 mounted within a drilled hole 31 in the stock. The rear end of the hole 31 is enlarged asat 38, see Fig. 1, to provide a shoulder 39 adapted to support a threaded cap 40 of the tubular section 36, the forward end of .the section 36 being threadedlyengaged with the rear end of the tubular member 35. The latter is provided with an enlarged head 4I at its forward or receiver end, the head being substantially U-shaped as shown in Fig. 7 to it into the inverted U-shaped recess 23 in the rear wall o1' the receiver, and is provided with a peripheral flange 42 adapted to seat on the front face of the ange 24. Thus, by turning the threaded cap 40 of the extension 36, the tubular member 35 tends to be retracted within the stock thus drawing its flanged head 4I into rm engagement with the ange 24 and simultaneously drawing the reduced end 23 of the stock into rigid engagement with the rear wall 26 of the receiver. A

'I'he tubular member 35 serves as a supporting means for a coil compression spring or action spring 43, the rear end of which engages a suitable plug (not shown) in the rear end of the tubular member 36. A suitable action spring -follower or pilot 46 is freely carried by the forward end of the spring and has an indentation 41 constituting a bearing surface for the reduced rear end 44 of an action slide link or strut 43. 43 is a suitable abutment seated and secured within the mouth of the tubular member 35 to retain the spring pilot 46 when the gun isY disassembled.

It can be seen, therefore, that the

tubes

36 and 36 and action spring 43 can be completely assembled and placed in position in the rear wall 22 of the receiver following which the stock I1 can be mounted on the tubular members 35 and 36 and securely fastened to the receiver by turning up the cap 40 on the threaded end of the tube 36.

Barrel extension The forepart of the receiver is constructed in substantially the manner described in the above mentioned patents to reciprocatingly support the barrel and barrel extension which are threadedly joined together in the usual manner. In the present embodiment, however, the barrel extension 55 is substantially longer than heretofore practiced, its forward end extending further along the barrel i6 so as to allow the use of a shortened receiver I5. This feature contributes to a saving in weight, especially if the receiver is formed of a heavy metal. It is proposed, however, to form the receiver shown and described herein as a die casting of a relatively light metal alloy having substantially the characteristics of forged aluminum, thus effecting a 'considerable reduction in weight.

,The rear portion of the barrel extension 66 is chamfered as at 56 to conform to the downwardly sloping curve 51 at the rear end of the receiver, which construction permits full recoil of the barrel extension such that the breech bolt, which is locked thereto, may recoil to a position adjacent the rear wall 22 of the receiver.

An aperture 5B is formed in the top of the barrel extension 55 for locking the bolt thereto as hereinafter described. The barrel extension is also provided with a shell ejector which, as shown in Fig. 10, comprises a shoulder 53 formed by intersecting grooves 590 and 59 I said shoulder being adapted to engage the rim of a spent shell to eject the shell from the receiver as hereinafter described. 'Ihe longitudinal groove 59| provides some clearance for the head ot a bolt locking latch hereinafter described, although not sulcient clearance to permit the latch to function while within the barrel extension.

Breech block assembly l Within the receiver is located a breech closure means 60 which is of the bolt type and which includes a supporting means hereinafter termed a carriage or action slide 6I associated therewith, the bolt and slide being confined in the usual manner to movement back and forth in the receiver.

The bolt 60 is provided at its forward end and on the right side thereof with a yielding extractor 62, as shown in Fig. 2, which projects slightly beyond the forward end of the bolt and is accommodated in the usual form of slot provided in the side of the barrel and barrel extension.

Referring to Fig. 2a, the breech block or bolt 60 is drilled longitudinally as indicated at 64 to support a reciprocable ring pin 65 and is apertured as at 66 to accommodate a bolt locking block 61. The latter is a sector shaped member having a protuberance 68 on its upper edge adapted to be entered into the aperture 68of the barrel extension and a bifurcated projection comprising a pair of spaced parallel claws 6 3 on its lower edge, the claws having cam surfaces 1n and 1I. The apex or nose v'I5.of the sector `the above mentioned patents.

open semicylindrical bearing 16 formed transversely in the forward wall of the aperture 66.

l Referring to Figs. 11 and 12, the sides of the breech bolt have apron portions 11 provided with parallel grooves 18 on the inner walls thereof, the grooves extending forwardly from the rear end of the bolt and terminating substantially midway of its length. These grooves are arranged to accommodate cooperating flanges 19 formed on the rear end of the carriage or slide 6|, the carriage being slidably assembled on the bolt by engaging its flanges 19 in the grooves 18.

The slide or carriage 6|, as shown in Figs. 2a and l2, comprises a base having flanges 8| adapted to fit in grooves (not shown) formed in the usual manner in the sides of the receiver, whereby the slide may reciprocate freely therein. A spring pressed lug B2 is pivotally supported centrally in a slot 83 in the forward end of the slide and projects downwardly normally to form a secondary cartridge stop 84, such as described in Opposite the lug 02, but at the rear end of the slide, is a second slot 85 adapted to accommodate the forward end of the action-slide link or strut 48 which is pivotally secured within the slot 85 and provided with a camming surface 81 adjacent its rear end. A fixed projection is formed on the bottom surface of the slide and comprises a camming lug 89 adjacent the right hand edge of the slide adapted, as hereinafter described, to cooperate with the cam surface of a lug B (see Fig. 8) mounted on a carrier locking latch |45 for automatically unlocking the carrier whenever the slide and bolt are in closed position. This particular construction is designed to permit one hand loading of the rearm. As shown in Figs. 3 and 4, 95 is a notch in the bottom of the slide adjacent its left hand edge for locking the slide in its rearmost position in the receiver.

The rnidportion of the slide is extended upwardly and is provided with a recess 92, the inclined walls of which constitute camming surfaces 93, 94 adapted to cooperate with the cam surfaces 1|, 10 respectively of the locking block claws 69.

Thus, when the bolt 60 and slide 6| are assembled in the receiver, as shown in Figs. 2 and 2a, wherein the slide is moved to its most advanced position relative to the bolt, the cam surface 94 of the slide has engaged and displaced the cam surface of the locking block upwardly until the latter is supported on the surface 9| of the slide, which surface is inclined to provide an adequate contact area between slide and lock.

bly will recoil rearwardly as a unit being retarded by the resisting force of the action spring 43 acting through the action spring strut 48, and the barrel restoring spring (not shown). The rearward excursion of the locked parts may be stopped by the rear wall 22 of the receiver and thereafter the parts will begin their return movement under the force of the compressed action spring 43 and barrel restoring spring.

In this rearward position which may be termed a semicylindrical bearing surface |02,

lthe rearward recoil position, a dog |35, hereinafter described, is arranged to engage in the notch '95 in the lower surface of the slide and hold the slide in its rearward position, but, the bolt, barrel and barrel extension are free to move forwardly relative to the slide. The forward movement of the breech block relative to the Slide brings cam surface 1| of locking block claw 69 into engagement with cam surface 93 of the slide whereupon the locking block pivots downwardly from the Fig. 2a position to the Fig. 3 position. The barrel and barrel extension continue their forward movement to their normal position, but the breech block, locking block and action slide remain retracted and in the relative position shown in Fig. 3 until the action slide has been unlocked for forward movement in the manner hereinafter described.

If there is ashell in the barrel chamber, such shell, due to its engagement by the extractor 62, above described, remains in contact with the breech bolt face, the barrel being stripped oi from the shell and the shell being subsequently ejectedl through the lateral port 2| in the receiver in the usual manner.

Subsequent release of the slide, as hereinafter described, will permit the bolt and slide to move forwardly, urged by the force of the compressed action spring 43, to breech closing position. It will be clear, however, that, due to a comparatively great inertia of the bolt 60 and to the fact that the slide 6| is urged forwardly by the spring 43,there will be a tendency for the bolt and slide to move relative to each other and thereby to again elevate the locking block 61, in which event the block would frictionally engage the top wall of the receiver l5 creating a drag or slowing down of the action and considerable wear between the parts. It is also probable that a camming action wo-uld be set up forcing the ilanges 8| of the slide 6I down in the grooves of the receiver, thus adding to the frictional retardation of the action.

Locking block latch To prevent these occurrences, a locking block latch is provided for automatically locking the locking block 61 to the bolt 60 and the bolt to the slide 6| when the latter is in its rearward recoil position.

Referring to Figs. 2a, 5 and 11, the latch comprises a pin |00 supported in a hole drilled transversely into the bolt, the longitudinal axis of the hole being displaced rearwardly slightly of the rear wall |0| of the aperture 66, thus effecting The shank of the pin or latch |00 is provided at one end with an axially drilled hole adapted to accommodate a coil compression spring |04. Adjacent this same end of the pin is a substantially rectangular block or key |05 formed integrally with and projecting laterally from the shank of the pin. The opposite end of the pin or latch is provided with a laterally projecting substantially rectangular head |06 having an oblique or cam surface |01.

The shank of the pin is milled dat between the key |05 and the head |06 so as to provide a substantially at surface |08 adapted to lie flush with the surface of the aperture wall I0l. .Also

substantially rectangular slots |09 are formed in the edges of the drilled hole |02 in the bolt 60 and on opposite sides of the aperture 66 to accommodate the rectangular key and head portions of the pin so as to prevent rotation thereof.

When the latch is assembled inthe bolt. its coil compression spring |04 seats in the bottom of the drilled hole |02 and tends to urge the latch key |05 and head |06 outwardly from the wall of the block. Normally, that is to say, whenever the bolt is locked to the barrel extension, see Fig. 2, the latch |00 is forced into its retracted position within the bolt against the force of the compressed spring |04 by engagement of the head |06 of the'latch in the grooved portion 59| of the inner wall of the barrel extension 55. However. when the barrel extension is stripped off of the bolt 60 following the retraction of the boit locking block 51 by the relative displacement of the bolt and slide, the latch head |06 is freed and springs outwardly urged by the spring |04.

Simultaneously the key |05 moves into engagement with a recess ||0 provided in an adjacent face of the locking block 61. thereby locking the block in its retracted position in the bolt. Consequently, the bolt and slide are also eectively locked together in the relatively displaced position and may move forward as a unitto breech closing position.

Although the description thus far has been of the automatic functioning of the bolt andY slide, manual retraction of the slide and subsequent rearward movement of the bolt to breech open position may be accomplished by the usual operating handle. The `latter comprises a finger engaging portion ||5 shown in Figs. 2a and 9 having a block H6, the latter being adapted to be slidingly received in a slot formed in the right hand side of the bolt, the block being adapted to extend inwardly into a suitable recess ||8 formed in the slide. A suitable wire spring ||9 is mounted in the slide adjacent the recess and arranged to bear upon the outer surface of the block I i6 to secure it to the slide.

From the position shown in Fig. 2, the action may be opened manually by pulling back on the operating handle ||5. thereby initially moving the slide 6| relative to the locked bolt 60, retracting the bolt locking block 6| from locking engagement with the barrel extension 55 and engaging the claws 69 of the block 61 in the recess 32 of the slide. Further pulling on the operating handle will move both the bolt and slide to their rearward recoil position, wherein the parts are' arrested by the dog |35 engaging the notch 95 of the slide as mentioned above. l

It will be observed that, during manual retraction of the` bolt, the locking latch head |06 is released from engagement with the inner wall of the barrel extension, and, consequently, springs outwardly whereupon the key |05 enters the recess ||0 in the locking block 61 and locks the block to the bolt. The bolt and slide are, at the same time, locked in their initially displaced positions (Fig. 4) and remain so locked until the parts are again returned to breech closing position.

When the bolt .and slide arrive in breech closing position, the cam surface |01 of the latch head |06 engages the adjacent wall 59| of th'e barrel extension (see Fig. 10) and is forced inwardly, thus removing the key |05 from the recess I0 of the locking block and unlocking the block 61 from the bolt. The bolt and slide are thus freed, whereupon the slide 6|l urged by the action spring 43. moves relative to the bolt 60 by an amount equal to the initial displacement of the slide with respect to the bolt, thereby again elevating th'e block 61 into the aperture 58 of the barrel extension.

' 8 Firing Mtl An additional function automatically eected' end, the firing pin is provided with a depending lug |20 at its rear end (see Fig. 2a) the lug projecting into the path of the after part |2| of the slide. Hence, asthe bolt moves forwardly with respect to the slide at the rearward recoiling po sition as above described, the firing pin 65 will be moved rearwardly in the breech block positively withdrawing its opposite end from the face of the breech bolt.

It will be seen also that since the breech block and slide are locked together against relative displacement while the parts move forward to breech closing position, the ilring pin will be held in its rearward position and not obstruct the loading of a fresh shell into the breech nor be subject to injury. When the bolt is in breech closing position, the relative movement of the slide and bolt, which accompanies the unlocking of the locking block 61 and bolt 60 and the locking together of the barrel. barrel extension and bolt assembly,

disengages the firing pin 65 from the slide 6| thereby freeing the pin so that it may move forwardly when subsequently struck by the hammer.

Cartridge carrierv Figs. 2 and 8 show the cartridge carrier which comprises spaced parallel side arms |20 pivotally.

supported on trunnions |23 mounted in the side walls of the receiver. The shape of the carrier and its arms is such that it can be suitably made and formed from sheet metal. Cartridges are fed onto the carrier in any usual manner as described in detail in the above mentioned Loomis patent. The left hand arm of the carrier, as shown in Fig. 3. is extended rearwardly beyond the trunnions |23 and is provided with a tapered nose portion |20 adapted to be accommodated in an open V-shaped slot |29 formed in one end of a carrier link |30 which is pivotally mounted at its opposite end |3| in a recess |32 formed in a trigger plate |33 hereinafter described. Pivotaliy secured on the inside face of the carrier link |30 by a lap joint construction (see Fig. 13) is the slide locking dog |35 having a nose provided with a sloping surface |36. A substantially vertical hole |31 is drilled upwardly through th'e bottom edge of the link and forwardly of its pivot point |32 into a recess |34 of the lap joint. A coil compression spring |38 is mounted in the hole |31, the spring being supported at its lower end on a shelf formed adjacent the recess |32 in the trigger plate. The upper end of the spring |38 supports a pin |39 adapted to project up into the lap joint recess |34 and to engage a shoulder |40 on the bottom of the dog |35. The pin |33 engages the shoulder |40 rearwardly of the pivot point |4| of the dog, thereby pivoting the dog |35 counterclockwise with respect to the link as seen in Fig. 3, whereby shoulders |42, |43 of the dog |35 and carrier link |30 respectively formed by the lap joint construction are held in contact. The force of the spring |30 is thus transferred by the abutting shoulders |42, |43 to the plvotedlink |30 at a point forward of its' pivot point |3|, thereby urging the link to pivot clockwise. 'Ih'e clockwise rotation of the link 30 is limited by a shoulder |44 formed adjacent the recess |32 in the trigger plate |33.

It will be clear. on reference to Figs. 3 and 4, that the dog |35 is free to pivot clockwise with respect to the link |30 against the urge of the spring |38, but that when the nose |36 of the dog is engaged in the notch 95 of the slide as th'e latter begins to move forward from its rearward recoil position, the dog |35 is urged counterclockwise thereby pivoting the carrier link |30 counterclockwise, as shown in Fig. 4, against the force of the relatively light spring |38. Thus a force is set up tending to pivot the arm |28 of the carrier clockwise on its trunnions |23 which force will elevate the forward end of the carrier when the latter is unlocked. I

The carrier |22 is locked against upward movement by means of a carrier locking latch |45 of the type more fully described in the Loomis patent, 1,931,262. However, the locking latch of the present invention has been modified in one respect as shown in Fig. 8, wherein an upwardly projecting lug 90, having a cam surface, is mounted on the head end of the latch, which is the end adapted to engage the upper surface of the carrier. This cam lug provides means for automatically unlocking the carrier whenever the slide and bolt are returned to their closed positions, the cam 90 being engaged and deflected outwardly from engagement with the carrier by the camming lug 89 which depends from the bottom of the slide as hereinabove described.

Fire control assembly The fire control mechanism, as shown in Figs. 2, 3, 3a, is assembled on the trigger plate |33 which, if desired, may be made of an aluminum alloy or other light weight metal so as to lighten the gun. The trigger |50 is mounted in a conventional manner on a pivot pin |5| in the trigger plate |33, its rear end portion being adapted to engage a transversely disposed safety bolt |52, the construction of which is similar to that shown in the above-identified Loomis patent.

The forward portion of the trigger extends upwardly through a slot in the bottom of a trough |53 in the trigger plate, as seen in Fig. 3a, substantially vertically above and in line with the trigger pivot pin |5| and has a ledge |54 and a lip |55 formed on its upper end. A sear |56 is pivotally mounted in the trough |53 in front of the trigger pivot pin |5| and is connected to the trigger by a link |51 which is pivotally connected at its opposite ends respectively to one arm of the sear and to the trigger at a point adjacent its lip |55. Drawing the trigger |50 rearwardly pivots the sear |56 counterclockwise as viewed `in Fig. 2, thus releasing a hammer |53 which springs forwardly due to the force of the compressed hammer spring |59, the latter being housed within a well |60 in the forward part of the trigger plate and immediately to the rear oi a hammer pivot pin IBI.

|60. The hammer and sear, which are of the usual construction, embody the usual means for preventing doubling which does not require explanation. f

Trigger lock A trigger lock is provided to prevent movement of the trigger until the breech bolt Aand slide are in closed position. The lock comprises a block |10 pivoted by a transverse pin |69 in the trigger plate trough |53 above and between the upper ends of the trigger and sear and is pro.

It will be clear, however, that, by pivoting the block |10 counterclockwise, as seen in Fig. 2, against the force of the coil spring |14, the long arm |12 of the lock will be elevated above the trigger shoulder |55, thereby unlocking the trigger. The latter may then be actuated to displace the sear and release the hammer. When the block |10 is released, the force of the compressed spring |14 tends to return the longer arm |12 to its position overlying the ledge |54 of the trigger. If the trigger has been released by the shooter, its lip |55 will have been moved rearwardly out of the path of the arm |12 by the force of the trigger spring |80, and hence arm |12 will be free to lockingly reengage the trigger lip |55. If the trigger is held by the shooter so that the lip |55 of the trigger remains in the forward position, the arm |12 then temporarily engages on top of the lip from which position it will escape into locking engagement with the lip whenever the draft on the trigger is released.

The trigger locking block |10 is adapted to be automatically actuated by its knob |13 which is arranged -to be engaged by the cam surface 81 of the slotted action link or strut 48 and only when thel latter has been advanced to its most forward position, at which time the breech is always closed and locked by the bolt and slide as already described.

It will be evident, therefore, that for any other position of the strut, that is to say, when the breech is not fully closed, the locking block is constantly urged in locking engagement with the trigger.

As thus described, it is clear that the trigger plate |33 includes all elements of the fire control mechanism assembled together in operative relationship in a, single member removable as a unit from the receiver and that the carrier link |30 is readily separable from the carrier arm |20 without requiring removal of the carrier |22 from the rearm. The trigger plate is mounted in a suitable recess in the underside of the receiver and stock. A pair of fastening pins |32 and |83 are provided which t in transversely drilled holes in the trigger plate and receiver frame to secure thee@ tw@ members together. Suitablelocking l1 means for the fastening pins are shown at |84 and |85 and comprise resilient spring members suitably mounted in the receiver in engagement with the pins |82 and |83 respectively.

The operation of the rearm will be given with particular reference to some of the new improvements.

The weapon being in readiness for firing, as shown in Fig.' 2, with the breech bolt and slide locked to the barrel extension by the locking block 61 and the action strut 48 forward so that its cam surface 81 engages the trigger lock knob I 13 rotating it counterclockwise and removing the arm |12 from engagement with the trigger shoulder |55, the trigger |50 is free to be drawn rearwardly. The trigger will pivot about pin |5| moving sear |56 forwardly thereby disengaglng the hammer |58 permitting it to rotate counterclockwise under the force of the hammer spring |59 until it strikes the rear end of the firing pin 65. The force of the explosion acting against the breech bolt assembly will drive the latter to the rear end of the receiver.

The vs'otted strut 48, which is pivoted to the slide, likewise travels rearwardly compressing the action spring 43 and disengaging the cam surface 81 of the strut from the trigger lock knob |13, the latter thereupon beingspring urged into locking engagement with the shoulder |55 of the trigger when the Itrigger pressure is removed.

As the slide or carriage 8| moves rearwardly, its lower surface and notch 95 pass over the carrier link dog |35, the latter yielding clockwise, while the displacement of the secondary eatridge stop 84 will allow a new shell to move onto the carrier |22, the latter being held in its downward position by thecarrier locking latch |45.

As the force of the barrel restoring spring and action spring 43 start the locked bolt assembly forward, the nose of the carrier link dog |35 is engaged in the notch 95 of the slide which tends to pivot the dog and carrier link counterclockwise. However, since the carrier is locked in its downward position` by the carrier latch |45 until a new shell is completely advanced thereon, the

r carrier link anddog are also locked, and hence barrel extension from the bolt releases the lockf ing block latch |00, which springs outwardly and locks the locking block 61 in its retracted position in the bolt 60, the latter being simultaneously locked in its forward position relative to the slide. The relative movement of the bolt and slide may also move the depending lug |20 of theA firing pin rearwardly positively withdrawing the pin in the breech bolt.

The forward movement of the barrel and barrel extension brings the ejector shoulder 59 in contact with the rim of the spent shell which has been retained against the face of the breech bolt by the extractor 62, the cooperative effect oi the stationary extractor 62 and moving ejector 59 deflecting the spent shell through the ejecting port 2| in the side of the receiver.

By this time, a new shell has been advanced suilicientlyonto the carrier |22 so as to engage and release the carrier locking latch |45 and a1- l2 low the carrier to rotate upwardly or clockwise on its trunnions |23 as indicated in Fig. 4. The energy for rotating the carrier is furnished by the force of the action spring 43 acting through the slide 6|, carrier link dog |85, andcarrier link |80.

The carrier will rise with a new shell so as to position the shell in the breech, the next succeeding shell in the magazine being stopped in the usual manner by a projection |86 on the forward end of the carrier locking latch |45. With the release of the carrier, the dog |35 ig free to move counterclockwise and to be disengaged from the slide notch 95, whereupon the slide is released and the bolt and slide move forward to breech closing position. As explained above, the bolt locking block is at this time locked to the bolt by the latch |00, and hence cannot be displaced in a manner to frictionally engage the walls o! the receiver.

As the bolt and slide approach breech closing position, the face of the bolt engages the new shell and moves it forwardly into chambered position, The cartridge carrier is lowered, following the release of the slide and bolt, by the force of the compressed spring |38 of the carrier link |30 which pivots the link clockwise.

When the bolt has reached breech closing position, its forward movement is stopped and the head |08 of the locking block latch |00 is pressed inwardly into the bolt, by reason of its engagement with the inner wall 59| of the barrel extension, thus unlocking the bolt and slide, The slide is thereby freed from the bolt and moves forwardly relative thereto by the force of the action spring 43 acting through the strut 40 whereupon the locking block 61 is displaced upwardly in the bolt 60 and entered into locking engagement with the aperture 58 of the barrel extension. Simultaneously, the slide cam lug 89 engages the cam lug 90 oi' the latch |45 unlocking the carrier locking latch |45 to permit one hand loading while the ring pin 65 is released fromengagement with the slide in a position to be struck by the hammer, The firearm is then in readiness to be fired again.

A modification in the construction of the bolt and barrel extension is indicated in Fig. 14, wherein a secondary locking means is shown for locking the barrel extension to the bolt. To this end, the chamfered portion 56 of the barrel extension is provided on its top surface with a suitable slot cut back from the end thereof and terminating in a transversely disposed forwardly inclined edge 203.

The rear end of the breech bolt 60 is shown with a protuberance or rib 200 extending above the upper surface of the bolt and having a forwardly inclined edge or hook 202 adapted to cooperatively engage the inclined edge 203 of the' slot of the barrel extension when the bolt and barrel extension are locked in engagement by the locking block 61 which may be termed the primary locking means. The upper surface 204 of the rib 200 is inclined downwardly and rearwardly so as to form a substantially smooth, continuous surface with the chamfered surface 56 of the barrel extension.

Thus when the locked parts recoil due to the force of the explosion, the rear end of the barrel extension is positively locked to the bolt, thus obviating any tendency of the barrel extension to spring upwardly and frictionally engage the underside of the receiver.

While the above described construction is one 13 embodiment of the invention, it will be understood that the invention is not limited to the preelse details shown and described, but includes such departures therefrom as fairly fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In a firearm, the combination with a receiver, a. barrel, a barrel extension, a breech bolt having a transverse aperture, a locking block pivotally mounted in the transverse aperture of said breech holt and arranged to be moved into and from engagement with said barrel extension to lock and unlock said breech bolt to and from said barrel extension; of means to lock and unlock said locking block to and from said breech bolt comprising a pin slidably mounted partly in the transverse aperture of said breech bolt and a spring arranged to load said pin longitudinally normally to force said pin laterally out of said transverse aperture and to lock said locking block in said breech bolt, said pin being arranged to be engaged by said barrel extension and forced laterally into said transverse aperture thereby to unlock said locking block from said breech bolt.

2. In a firearm, the combination with a receiver; a recoiling barrel having a. barrel extension, the rear end of which is provided 'with a bevelled lip on the top edge thereof; breech mechanism comprising a. breech block; a, carriage for slidably supporting said breech block; primary locking means supported in said breech block and actuated by movement of said carriage relative to said breech block to lock said block to said barrel extension; and secondary locking means comprising an upwardly extending hook on the top of said breech block adjacent its rear end arranged to overlie the bevelled lip of said barrel extension when said breech block and barrel extension are locked by said primary locking means to hold down the rear end of said barrel extension and prevent frictional engagement thereof with the top of the receiver during recoil of the breech block and barrel extension.

3. In a firearm having a receiver, breech mechanism in said receiver comprising a reciprocable carriage block having an axially aligned vertically projecting rib; a breech block mounted on said carriage having a central groove to receive said rib; and means to lock said breech block to said carriage so as to enable longitudinal movement only of said breech block relative to said carriage and to accurately guide said breech block during said movement, said means comprising longitudinally extending ribs on opposite sides of said central groove constructed and arranged to interlockingly engage longitudinally extending ribs on opposite sides of said rst mentioned rib.

4. Inafirearmhavlngareceiver,breechmechanism in said receiver comprising a, reciprocable carriage block having an axially aligned vertically disposed rib and longitudinally extending tongues and' grooves on opposite sides on said rib; a breech block mounted on said carriage having a, central groove to receive said rib; and means to lock said breech block to said carriage so as to enable longitudinal movement only of said breech block relative to said carriage and to accurately guide said breech block during such movement, said means comprising longitudinally extending tongues and grooves on opposite sides of said central groove constructed and arranged to interlockingly engage the tongues and grooves of said carriage.

OLIVER H. LOOMIS.

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

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