US3360878A - Firing mechanism for bolt-action firearm - Google Patents

Description

Jan. 2, 1968 l} T. R. ROBINSON, JR ,8

FIRING MECHANISM FOR BOLT-ACTION FIREARM Filed/ Sept. 1, 1966 24 *5; TIL/OM45 1e Roam/so we 25 a ,3 we 62 W Q? new INVENTOR United States Patent ABSTRACT OF THE DISCLOSURE The disclosure deals with a sear connection with a firing pin in a firearm, which comprises a part with integral key and lug formations of which the key formation is in register with a groove in the firing pin within the bolt sleeve bore and the lug formation extends through a slot in the bolt sleeve to the outside of the latter and there has a sear nose, with the part having in the slot freedom of motion with the firing pin over a certain range to one end of which the lug formation is urged by the operating spring of the firing pin, and there being further provisions for locking the key formation in the groove over a first part of said free-motion range to said one end thereof, and the part being with its key formation insertable and removable through the slot into and from register with the groove in the firing pin on depressing the latter into a part of the free-motion range other than said first part thereof.

This invention relates to firearms of bolt-action type in general, and to firing mechanisms of firearms of this type in particular.

The firing mechanisms of firearms of this type conventionally provide a firing pin, a main spring, a bolt sleeve and a cooking piece, with these parts being customarily preassembled as a unit, referred to conveniently as a firing unit, to lock the main spring in loaded condition for subsequent facile assembly of this unit with the breech bolt. customarily, the firing pin extends rearwardly through a bore in the bolt sleeve and the spring is interposed between the forward end of the sleeve and an intermediate shoulder on the pin, with the bore in the sleeve being rearwardly enlarged for fitted reception of the cocking piece which is secured to the firing pin, in most cases releasably, as by a cross pin, bayonet connection or threading, for example. In preassembling these parts, the firing pin is passed through the spring and then through the bolt sleeve, whereupon the sleeve is forced further over the pin against the spring for preloading the latter in compression and for projection of the pin beyond the sleeve sufficiently to permit the application of the cooking piece to and its connection with the projecting pin.

While these preassembled prior firing units are satisfactory in most respects, they do have shortcomings in a few but important respects. Thus, the requirement of enlarging the pin bore in the bolt sleeve and fitting the cocking piece in the enlarged bore not only makes for extensive and rather intricate machining of the sleeve as well as of the cocking piece with its usually depending integral sear lug, but also makes it imperative to provide the bore in the sleeve as a through-bore in order'to receive the cocking piece and permit its securement to the firing pin. Accordingly, the bolt sleeve and cocking piece become rather expensive items, and the assembled firing unit is also potentially hazardous in action in that the through-bore in the sleeve offers a most direct leakage path to a shooters face for powder gases from a ruptured primer, for example. Further, the usual connection between the firing pin and cocking piece either further complicates the machining of these parts with ensuing further 3,360,878 Patented J an. 2, 1 9% increase of their cost, as in the case of a bayonet connection, for example, or requires special tools and considerable skill in making the connection between these parts under the aggravating force of the preloaded main spring, as in the case of pinning the parts together, for example.

It is among the objects of the present invention to provide for a firearm of this type a preassembled firing unit which is of rugged construction, yet is highly reliable and accurate in its performance for the longest time, and which above all has none of the aforementioned shortcomings of the prior firing units.

It is another object of the present invention to provide for a firearm of this type a firing unit which for its lock in assembled condition and for movability of the sear lug with the firing pin into its cocked and firing positions, employs a single master part with key, lug and lock formations, of which the key formation is within the bolt sleeve received by the firing pin for movement therewith, the lug formation extends through a longitudinal slot in the bolt sleeve to the outside thereof where it has a sear nose in cooperative relation with a trigger-operated sear, and the lock formation is received in a guideway in the bolt sleeve in which it locks the master part against removal from the pin and sleeve parts. This master part is thus highly advantageous not only because of its structural simplicity and low cost as well as multiple functions, but also because it eliminates the heretofore rear enlargement of the pin bore in the bolt sleeve and the therein fitted cocking piece with its sear lug and the attendant shortcomings thereof. Moreover, the merit of this master part is even enhanced in that it reduces the number of parts of the unit below that of previous firing units by replacing the heretofore more or less intricate cocking piece and whatever part or parts are involved in the operative connection of the cocking piece with the firing pin.

It is a further object of the present invention to provide for a firearm of this type a firing unit which for the assembly of the aforementioned master part with the other parts of the unit merely requires lateral insertion of the master part through the slot in the bolt sleeve into keyed relation with the firing pin while temporarily holding the sleeve and pin parts and the main spring overcompressed to an extent at which the guideway in the sleeve part is displaced from the lateral entry path of the lock formation of the master part, so that on subsequent mere release of the compressed parts and their ensuing expansion to the limit of the slot in the sleeve part the lock formation of the master part will be received by the aligned guideway in the sleeve part and thus lock the unit for normal operation.

Another object of the present invention is to provide for a firearm of this type a firing unit of which the firing pin has for preferred fitted reception of the key formation of the master part a simple milled transverse groove, and the aforementioned lock formation of the master part and its guideway in the bolt sleeve are formed by the key formation of the master part and the pin bore in the bolt sleeve, respectively, by simply extending the key formation and its receiving groove in the firing pin so that over the normal operating range of the latter between its cocked and firing positions the key formation extends longitudinally part-way into the pin bore in the bolt sleeve beyond the slot therein and is shaped to be in substantial formfit with the wall of the pin bore over its extent therein. With this arrangement, the lock of the master part in the unit, and hence the lock of the entire unit, is achieved with the same simple structure and virtually the same simple machining of the parts with which the key connection of the master part with the firing pin is achieved.

A further object of the present invention is to provide for a firearm of this type a firing unit of which the aforementioned master part has on its lug formation also a shoulder for cooperation with the usual cam formation on the breech bolt for cocking the firing pin on unlocking the bolt handle from the receiver in usual manner for retraction of the breech bolt, thereby adding still another function to the multiple functions of the master part.

Another object of the present invention is to provide for a firearm of this type a firing unit in which the pin bore in the bolt sleeve is preferably and advantageously closed in the rear, yet ready visual or touch indication of the cocked or non-cocked condition of the firing mechanism may be provided for, if desired, by simply extending the lug formation of the aforementioned master part rearwardly to the outside of the usual rear knob formation on the bolt sleeve in a guideway which preferably and advantageously is formed by complemental and easily machined grooves in this knob formation and in the receiver. Further, with this arrangement, the master part, and with it the knob on the bolt sleeve, have additional guidance in action of the firing unit, and powder gases from a ruptured primer also have a quite tortuous rearward path and will be largely dissipated internally with no hazard to a shooters face.

It is another object of the present invention to provide for a firearm of this type a firing unit of which the aforementioned master part is a fiat blank-like part of simple configuration which is readily machined to fairly close tolerances and, hence, lends itself to efficient and lowcost production.

Further objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

FIG. 1 is a fragmentary longitudinal section through a firearm embodying the present invention;

FIG. 1A is another fragmentary longitudinal section through the same firearm;

FIG. 2 is a fragmentary end view of the same firearm as seen in the direction of the arrow 2 in FIG. 1;

FIG. 3 is a fragmentary section through the firearm as taken on the line 3--3 of FIG. 1;

FIG. 4 is a fragmentary section similar to FIG. 1, but showing certain parts of the firearm in different operating positions;

FIG. 5 is a perspective view of a prominent part of the firearm;

FIG. 6 is a reduced section through a prominent operating unit of the firearm; and

FIG. 7 is a reduced longitudinal section through a firearm embodying the invention in a modified manner.

Referring to the drawings, and more particularly to FIGS. 1 to 4 thereof, the reference numeral 10 designates a bolt-action firearm having a receiver 12 secured in usual manner to a stock 14 and having mounted in its front end a barrel (not shown). Received in a bore 16 in the receiver for sliding and turning movement therein is a breech bolt 18 having at its rear end a cam formation 20 and also a bolt handle 22 with which to turn the bolt 18 into lock and release positions as well as to move the same into its open and closed positions. The breech bolt 18 and receiver 12 also have a conventional lug and bayonet-slot type connection (not shown) which looks the bolt 18 in its closed position on turning the handle 22 into its full-line position in FIG. 2, and which releases the closed bolt for retraction on turning the handle 22 into its dotted-line position in FIG. 2, with this connection also serving to arrest the bolt against turning from its angular release position on its retraction into open position and return to its closed position. The receiver 12 also has a bottom slot 24 into which extends a mounting bracket 26 for parts, including a pivoted sear 28, a sear spring 30 and a trigger 32, with the bracket 26 being received in an aperture 34 in the stock 14 and suitably mounted in the latter. The firearm described so far may be entirely conventional and forms no part of the invention except insofar as it enters into combination therewith.

The firearm 10 further provides a firing unit 36 according to the present invention, which comprises a bolt sleeve 38, a firing pin 40, a main spring 42 and a master part 44 (FIGS. 1 and 4). The bolt sleeve 38 has a longitudinal bore 46 and is provided with a customary external thread 48 for its reception in and assembly with an internally threaded rear length of the breech bolt 18. A rear part 50 of the bolt sleeve 38 is preferably enlarged and shaped as a knob which in closed position of the bolt (FIG. 1) blends tastefully with the receiver and bolt handle and lends these parts a pleasant streamlined appearance. The knob formation 50 of the bolt sleeve 38 and the receiver 12 have in this instance machined complemental surfaces 52 and 54 (FIGS. 3 and 4) by which the part 50 is guided on the receiver into and from bolt closing position.

Slidably received in the bore 46 of the bolt sleeve 38 is a rear length of the firing pin 40 another length of which projects forwardly from the bolt sleeve and is provided with a collar formation 56 (FIG. 1A). Surrounding the firing pin 40 and interposed between the collar formation 56 thereon and the front end of the bolt sleeve 38 is the main spring 42 which is of compression type and preloaded normally to urge the firing pin in forward direction and into its firing position in which the exemplary tapered flank 58 of the collar formation 56 thereon rests against a similarly tapered shoulder 60 in the breech bolt 18 (FIG. 1A).

The master part 44 performs multiple functions one of which is operatively to connect the firing pin 40 with the sear and trigger mechanism. To this end, the master part 44 has integral key and lug formations 62 and 64 of which the key formation 62 serves for connecting the part 44 with the firing pin 40 for movement with the latter, and the lug formation 64 provides a sear nose 66 on the outside of the bolt sleeve and in cooperative relation with the sear 28 (FIG. 1). More particularly, the firing pin 40 is within the bore 46 in the bolt sleeve 38 provided with a transverse groove 68 in which the key formation 62 of the master part 44 is fittedly received, while the lug formation 64 projects through a longitudinal slot 70 in the bolt sleeve to the outside thereof where it is provided with the sear nose 66 (FIGS. 1 and 3). Provisions are also made for locking the master part 44 to the firing pin 40 in its assembled relation therewith over the action range of the firing pin between its cocked and firing positions (FIGS. 1 and 2) and over the retraction range of the breech bolt 18 from its closed position in FIG. 1. To this end, the bolt sleeve 38 is provided with a longitudinal guideway in which is slidably received a lock formation on the master part 44. Preferably and advantageously, this guideway in the bolt sleeve 38 is formed by part of the bore 46 therein, and the lock formation on the master part 44 is formed by part of the key formation 62 thereon. Thus, and as shown in FIG. 1, the key formation 62 has a length 72 which projects forwardly beyond the lug formation 64, and part of this key length 72 is over the action range of the firing pin fittedly received in the sleeve bore 46 (FIGS. 1 and 4) and thus locked between this bore 46 and the groove 68 in the firing pin (see also FIG. 3).

The slot 70 in the bolt sleeve 38 is of more than adequate length to afford the lug formation 64 therein of the part 44 the necessary freedom of motion which the latter requires in order to move with the firing pin 40 over the action range between its cooked and firing positions (FIGS. 1 and 4). Further, the lug formation 64 preferably extends at 74 rearwardly beyond the bolt sleeve 38 at least in the cocked condition of the firing pin for visual or touch indication of this condition to a shooter. To this end, as well as to afford the master part 44 the necessary freedom of motion with the firing pin and lock it in keyed relation with the firing pin over the action range of the latter, the master part described so far is of general Z-shape with opposite arms a and a and a connecting yoke y (FIG. 1), of which arm a forms the key formation 62 and the yoke y and other arm a form the lug formation 64, with the yoke y being that part of the lug formation which is within the slot 70 in motion-limit relation with the opposite ends 76 and 78 of the latter, and arm a being that part of the lug formation which provides the sear nose 66 and also extends rearwardly beyond the bolt sleeve in the cocked condition of the firing pin. This arm a of the master part 44 is preferably guided between the slot 70 in the bolt sleeve 38 and the rear end thereof in a simple groove 80 in the sleeve which is prefrably continuous with and of the same width as the slot 70 (FIGS. 1 and 2), and this arm a is preferably further guided in a groove 82 in the receiver 12 which is complemental to the groove 80.

The master part 44 preferably and advantageously has another follower, formation 84 which is in cooperative relation with the cam formation 20 on the breech bolt 18 for cocking the firing pin into a position like or similar to that in FIG. 1 on turning the bolt handle 22 into its dotted-line position in FIG. 2. It is in this position of the bolt handle that the bolt 18 is released for retraction from its closed position to eject a fired cartridge from the receiver and admit a fresh cartridge thereinto, in this example from a magazine 86 (FIG. 1). The bolt 18 will, on its subsequent return into closed position, advance the fresh cartridge into the firing chamber (not shown) and bring the sear nose 66 on the master part 44 into engagement with the then cocked sear 28 for retaining the firing pin in its firing position (FIG. 1) when on subsequent turning of the bolt handle 22 into its full-line bolt-locking position (FIG. 2) the cam formation 20 on the bolt is turned out of register with the follower formation 84 of the part 44 (FIG. 1). The firearm is then ready for firing the cartridge on pulling the trigger 32, with the cam formation 20 on the bolt 18 being then out of the path of the follower formation 84 of the part 44 on its movement with the firing pin 40 into firing position (FIG. 4). The follower formation 84 of the master part 44 is then in position (FIG. 4) for renewed cooperation with the cam formation 20 on the bolt 18 in recocking the firing pin 40 on turning the bolt handle 22 into its dotted-line boltreleasing position to start another loading cycle.

The firing unit 36 has many important advantages structure-wise and cost-wise. Thus, its structure is exceedingly simple and requires a minimum of simple machine operations of its parts. In this connection, the bolt sleeve 38 is of particularly simple construction and requires for its operative coordination with the firing pin 44 and sear nose 66 merely the bore 46 of uniform diameter and the slot 70 and groove 80 of uniform width. The firing pin 40 requires for its coordination with the sear nose 66 merely the transverse groove 68. The master part 44' is also an exceedingly simple piece of uniform thickness and simple shape (see also FIG. 5) which may readily be machined from an original blank in a minimum number of operations, with all but three surfaces of this part being plane. Insofar as the preferably coextensive follower formation 84 and forwardly extending length 72 of the key formation 62 of the part 44 and their curved joining surface 88 are concerned, these may readily be formed by transversely slotting the original part blank in a milling operation, whereupon the surface 90 of the key length 72 facing the follower formation 84 is simply turned into part-circular shape of the diameter of the bore 46 in the bolt sleeve 38 for its form-fit therewith (FIGS. 1, 3 and 4). Also, the preferably rounded follower surface 92 of the follower formation 84 of the master part 44 is obtained by simple machining.

The master part 44 of uniform thickness will, by virtue of its sliding fit in the slot 70 and groove 80 in the bolt sleeve 38 and in the groove 82 in the receiver 12, also effectively seal the rear of the sleeve and receiver against leakage into a shooters face of powder gases from a. ruptured primer which, instead, will harmlessly be dissipated within the receiver. To the latter end also, the bore 46 in the bolt sleeve 38 is preferably closed at the rear, as shown. Also, the follower formation 84 of the master part 44 is preferably arranged to be in sliding fit with the bolt sleeve 38 (FIGS. 1 and 4) for its additional lock to the bolt sleeve 38 and to the firing pin 40 over the action range of the latter as well as over the motion range of the breech bolt 18 into and from its closed position. The arrangement of the follower formation 84 of the master part 44 in sliding fit with the bolt sleeve 38 further adds to the rectilinear guidance of the master part in its motion with the firing pin 40, whereby on cooking the firing pin against the main spring 42 through cooperation between the cam formation 20 on the breech bolt and the follower formation 84 of the master part, any twist forces will largely, if not entirely, be avoided in the master part. To the latter end also, the parallel side walls 94 of the transverse groove 68 in the firing pin are inclined to the bottom wall 96 thereof in such wise that the rearmost sidewall 94 and the bottom wall 96 form an acute angle pointing to the rear end of the bolt sleeve 38 (FIG. 1).

The firing unit 36 is also easily assembled and locked in its assembled condition (FIG. 6) for its further facile assembly with the breech bolt 18 and the rest of the firearm. Thus, in assembling the parts of the firing unit 36, the main spring 42 is slipped over the firing pin 40, whereupon the rear end of this pin is, against the compression of the spring 42, introduced into the bore 46 in the bolt sleeve 38 on first turning the pin with its transverse groove 68 facing in the direction of the slot in the bolt sleeve 38. The spring 42 is then resting on the front end of the bolt sleeve 38 and will be increasingly compressed as the firing pin is introduced deeper into the bore in the bolt sleeve until the groove 68 in the pin is in full register with the slot 70 in the bolt sleeve, whereupon the master part 44 is with its key formation 62 inserted through the slot 70 into fitted reception in the groove 68 in the firing pin. The firing pin is then released, whereupon the parts 38 and 40 will under the force of the preloaded main spring 42 expand, in the course of which the projecting key length 72 of the master part 44 will axially enter the bore in the bolt sleeve until the surface 88 joining this key length and the follower formation 84 comes to rest against the adjacent end 76 of the slot 70 to stop the parts 38 and 40 against further expansion and also lock all parts of the assembled firing unit 36 against disassembly. The slot 70 in the bolt sleeve 38 is accordingly of sufficient length to permit depression of the springloaded firing pin 40 into the bore 46 in the bolt sleeve until the transverse groove 68 in the pin is in full register with the slot 70 in the bolt sleeve for the insertion of the master part, as well as its removal when required, through this slot. Ready assembly of the parts of the firing unit 36 and their lock in assembled condition by the master part 44 is thus another important feature of the present invention. In the course of assembling the firing unit 36 with the breech bolt 18, by simply threading the former into the latter, the shoulder 58 on the firing pin 40 will come to rest against the corresponding shoulder 60 in the breech bolt (FIG. 1A) whereupon the firing pin and the master part will be backed up in the bolt sleeve until the firing pin assumes the firing position in FIG. 4 at the conclusion of the assembly of the firing unit with the breech bolt, as will be readily understood. It is thus apparent from FIGS. 1 and 4 that the action range of the firing pin between its cocked and firing position lies within, but is spaced from both ends of, the free-motion range of the firing pin and master part relative to the bolt sleeve when the firing unit 36 is non-assembled with the breech bolt (FIG. 6).

While in the described exemplary firearm 10 the lug formation '64 of the master part 44 extends in the cocked condition of the firing pin rearwardy beyond the bolt 7 sleeve 38, FIG. 7 shows a modified firearm in which the lug formation 64a of the master part 44a is shortened and hidden from view, with the bolt sleeve 38a having at its rear end a. rib-like formation f8 which is received with a sliding fit in the groove 82a in the receiver 12a.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restric ive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. A firing unit for a bolt-action firearm, having a longitudinally bored bolt sleeve with opposite ends and a longitudinal slot between said ends and leading to said bore; a firing pin having a length with a transverse groove slidable in said sleeve bore; preloaded spring means urging said pin in firing direction; a part having integral key and lug formations, of which said key formation is in register with said groove for movement of said part with said pin, and said lug formation extends through said slot to the outside of said sleeve and there has a sear nose, with said lug formation having in said slot freedom of motion with said pin over a certain range and being by said spring means urged against one end of said slot to hold said pin at one end of said range; and means locking said key formation in said groove over a first part of the free-motion range of said pin extending to said one end thereof, and said part is with its key formation insertable and removable through said slot into and from register with said groove on depressing said pin into a part of its free-motion range other than said first part thereof.

2. A firing unit for a bolt-action firearm as in claim 1, in which said locking means provide a guideway in said sleeve in the direction of said bore therein, and a lock formation on said part projecting into and guided in said way over said first part of the free-motion range of said pin, but being retracted from said guideway over the remaining part of the free-motion range of said pin for insertability and removability of said part.

3. A firing unit for a bolt-action firearm, having a longitudinally bolt sleeve with front and rear ends and a longitudinal slot between said ends and leading to said bore; a firing pin slidable in said sleeve bore and projecting forwardly from said front sleeve end and having a transverse groove in said bore; preloaded spring means urging said pin in forward direction; and a part having integral key and lug formations, of which said key formation is in register with said groove for movement of said part with said pin and said lug formation extends through said slot to the outside of said sleeve and there has a sear nose, said lug formation in said slot is of shorter longitudinal extent than the latter to have freedom of motion with said pin over a certain range to the forward end of which said lug formation is urged by said spring means, a length of said key formation shorter than said free-motion range projecting forwardly beyond said lug formation in said slot and being slidably received in said sleeve bore and thereby lock in said groove over a corresponding length of said free-motion range from said forward end thereof, and said slot being of sufficient longitudinal extent to permit forcing said pin against said spring means and within said free-motion range into a position in which said groove is in full alignment with said slot for insertability and removability of said part through said slot into and from keyed relation with said pin.

4. A firing unit for a bolt-action firearm as in claim 3, in which said part is a longitudinal fiat blank-like piece of uniform thickness, and the width of said slot in said sleeve is substantially equal to the thickness of said piece.

5. A firing unit for a bolt-action firearm as in claim 3, in which said part is a longitudinal fiat blank-like piece of uniform thickness and of general Z-shape with opposite arms and a connecting yoke, of which one of said arms forms said key formation and the other arm and yoke form said lug formation, with said other arm being provided with said sear nose.

6. A firing unit for a bolt-action firearm as in claim 5, in which said sleeve has in its outer circumference a longitudinal groove in line with said slot and extending from the latter to said rear sleeve end, and said other arm is received with a sliding fit in said longitudinal groove.

'7. A firing unit for a bolt-action firearm as in claim 3, in which said groove in said pin has a bottom surface and parallel side surfaces so inclined to said bottom surface that said side surface nearest said rear sleeve end forms with said bottom surface an acute angle.

8. A firing unit for a bolt-action firearm as in claim 3, in which said sleeve bore is closed at said rear sleeve end.

9. A firing unit for a bolt-action firearm as in claim 3, in which said lug formation of said part has on the outside of said sleeve also a follower shoulder adapted for cooperation with a cocking cam of a breech bolt.

10. A firing unit for a bolt-action firearm as in claim 3, in which said part is a longitudinal fiat blank-like piece of uniform thickness having a transversely slotted forward end to form spaced prongs on said piece of which one prong constitutes said length of the key formation, and the other prong constitutes part of said lug formation on the outside of said sleeve and is in sliding engagement with the latter substantially over said length of the freemotion range for additionally looking said key formation in said groove.

11. A firing unit for a bolt-action arm as in claim 10, in which said other prong has a forward follower end adapted for cooperation with a cooking cam of a breech bolt.

12. A firing unit for a bolt-action firearm as in claim 3, in which said lug formation of said part has on the outside of said sleeve a shoulder, and said sleeve has an external thread for its assembly with a breech bolt, and said unit further comprises a breech bolt assembled with said sleeve and turnable relative to the latter into bolt release and lock positions, said bolt having stop means for said firing pin in firing position and a formation for cooperating with said shoulder in camming said pin into cocked position and for releasing it for movement in said forward direction into firing position, with the action range of said pin between its cooked and firing position being within but shorter than said free-motion range length and spaced from both ends of the latter.

References Cited UNITED STATES PATENTS 3,013,355 12/1961 Weatherby.

BENJAMIN A. BORCHELT, Primary Examiner.

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