US2601808A

US2601808A - Breech bolt lock and actuator for firearms

Info

Publication number: US2601808A
Application number: US49433A
Authority: US
Inventors: Howard R Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-09-15
Filing date: 1948-09-15
Publication date: 1952-07-01
Anticipated expiration: 1969-07-01

Description

.Fuly l, 1952 H. R. CLARKE ZSSS BREECH BOLT LOCK AND ACTUATOR FOR FIREARMS Filed sept. 15, 1948 s sheets-sheet 1 July E, 1952 H. R. CLARKE BREECH BOLT LOCK AND ACTUATOR FOR FIREARMS 5 Sheets-Sheet 2 Filed Sept. 15,

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ATTORNEVS H. R. CLARKE BRECH BOLT LOCK AND ACTUATOR FOR FIREARMS `luly l, 1952 '3 sheets-sheet 5 Filed Sept. 15, 1948 INVENTOR. l @WARD R 01:41am? ATTORNEYS Patented July 1, 1952 UNITED BREECH BOLT LOCK AND ACTUATOR FOR FIREARMS Claims. 1

My present invention relates to firearms and particularly to bolt action ries whether manual, semi-automatic, or fully automatic in their operation.

Where a firearm is to use ammunition developing high breech pressures, it is necessary to provide means to lock the closed bolt securely to the receiver. This locking of the bolt has customarily been accomplished by providing the receiver and the bolt with locking lugs disposed to be in mutual engagement when the bolt is closed and partially rotated.

While a bolt locked in that manner is adapted to be safely operated, it is objectionable, particularly where automatic or semi-automatic operation is required because excessive power is needed to rotate the bolt due to the fact that the gas pressure forces the bolt lugs tightly against those of the receiver.

In accordance with my invention, I provide a firearm that has its receiver formed with a pair of transversely alined pockets. The bolt, which is mounted in the receiver to reciprocate between closed and open positions, includes a bolt shell having locking arms pivotally connected to it to swing outwardly from an inoperative position in which the bolt shell is free to reciprocate into the pockets when the bolt is in its closed position. An actuator is slidable in the shell and includes a wedge portion engageable with the arms to establish a driving connection between the actuator and the bolt shell when the actuator is driven forwardly and to wedge the arms apart and into their pockets when the bolt shell is closed. I provide a shouldered member slidably connected to the bolt shell to move relative thereto into and out of aposition in which, when the locking arms are operatively positioned, its shoulders engage the free ends of the arms to lock them positively against being forced into their inoperative position. The member is also slidably connected to the actuator to provide predetermined movement of the actuator in either direction before it is moved thereby.

By this construction, my bolt is securely locked to the receiver but may be easily unlocked by driving the member rearwardly so that its shoulders do not block movement of the locking arms into their inoperative position. This requires minimum power since the shoulders are subjected to only a portion of the pressure on the parts that is developed when the firearm is fired and the power employed to unlock the bolt is not added to increase the friction between the locking arms and the receiver. While the actuator may be moved rearwardly by any means, I prefer that its rearward action be initiated automatically! in response to gas pressure with the lag between the movement of the actuator and the movement of the member serving both to time the unlocking of the bolt so that residual pressures in the barrel may be safely employed to ensure the completion of the travel of the bolt into its open position and to time the locking of the bolt when fully closed by the actuator.

A firearm in accordance with my invention also has many other features relating to the ease of its assembly and'disassembly and also to simple but reliable trigger controlled firing mechanism for use insemi-automatic or fully automatic operation.

In the accompanying drawings, I have shown embodiments of my invention whichV serve to illustrate these and other of its novel features and advantages. In the drawings:

Fig. 1 is a partly sectioned, fragmentary, side view of a rearm in accordance with my invention.

Fig. 2 is a horizontal section, on an enlarged scale, through the receiver of the firearm shown 'in Fig. 1.

Fig. 3 is a vertical section through the bolt.

Fig. 4 is a front end view of the bolt.

Fig. 5 is a section along the lines 5-5 of Fig. 1.

Fig. 6 is an exploded View showing the bolt parts in side view.

Fig. '7 is a bottom plan View of the bolt shell.

Figs. 8, 9, and 10` are sections, respectively along the lines 8 3, 9-9, and lll-i9, of Fig. 1.

Fig. 11 is a fragmentary view of the slide.

Fig. 12 is a section through the charging handle showing the means by which it is detachably locked to the slide.

Fig. 13 is a fragmentary and partly sectioned view showing the support of the barrel between the fore stock and the hand guard.

Fig. 14 is a bottom plan view of the hand guard.

Fig. is a section along the lines l5--I5 of Fig. 13.

Fig. 16 is a partly sectioned view of the firing mechanism shown in Fig. 1 and equipped with means to render its operation fully automatic.

Fig. 1'7 is a section along the lines I'l-l'l of Fig. 16.

Fig. 18 is a fragmentary plan view oi the control by which the firing mechanism is set Yfor either semi-automatic or fully automatic operation, and f Fig. 19 is a section through the ring mechanism of Fig. 1 showing the safety. i

In the embodiment of my invention shown in the drawings, I have indicated generally at the receiver of a semi-automatic or automatic rie. A chambered barrel 2| is threaded into the receiver 2|) and both are supported in a suitably inletted stock 22.

Within the receiver 2|) is a bolt generally indicated at 23. The bolt 23 is reciprocable between the closed position shown in Fig. 1 in which it seats a cartridge 24 in the chamber of the barrel 2| and an open position in which it is rearwardly of the port 25 through which empty cartridge cases are ejected. Forward movementof the bolt 23 from its open position results in anotherv cartridge 24 being picked up thereby from the,

magazine 26 and seated in the chamber of the barrel 2|.

In accordance with my invention, I, provide.

the receiver with one and preferably two cam pockets 21 which are shown as being transversely alined. (See Fig. 2.)

My bolt consists of a bolt shell 23 having at its forward end a cartridgeY engaging, recessed face 29, an axial chamber 30 opening through its rear end, and a transverse slot 3| intersecting the chamber 33. A pair of locking arms, generally indicated at 32, are pivotally connected to the bolt shell 28. Preferably, the locking arms 32 are formed with integral, slightly tapered pintles 33 adapted to enter correspondingly tapered bores 34 intersecting the ends of the slot 3| at its front edges. Each locking arm 32 includes an outer cam portion 35 complemental'in size and shape tothe cam pockets 21 and has on its inner surface a contact portion` 33 adjacent its pintle 33 and a ledge 31 adjacent its free end. The locking arms 32 are free to swingv into a housed inner or inoperative position in the ends of the slot 3| in which they do not interfere with the reciprocation of the bolt shell. 28 or outwardly into an operative position into the cam pockets 21. The locking arms 32 are so located that when their cam portions 35' are in the pockets 21, the bolt shell 28 is in its closed position.

My bolt also includes an actuator generally indicated at 38 and' having. a flange 39 engageable with the rear end of the bolt shell 28V and a portion extending into the bolt shellchamber 30 and terminating in a wedge 4|. The chamber entering portion 40 of the actuator 38 has a transverse slot 42 and the actuator. also has a rearward. extension 43 provided with a recess 44 in its upper edge. (See Figs. Band 6.)

When the actuator 38 is driven forwardly, its wedge 4| engages the contact portions` 36 of. the locking arms 32 and tends to wedge them outwardly until. restrained by the receiver so that a connection between the bolt shell 28 and the actuator 38 is established driving the bolt shell 28 forwardly intoits closedposition in which the locking arms 3.2 are free to swing outwardly into the cam pockets 21. tions. 36 of the arm 32 are rearwardly of but adjacent to the arm pintles 3.3,` the wedging Because the contact por-r Cil 4 tion in which its shoulders 45 underlie the locking arm ledges 31 thereby positively blocking movement of the locking arms 32. The key 45 is also slidable with reference to the actuator 38 since its slot 42 is dimensioned to require predetermined movement of the actuator 38 in either direction before the key 45 is picked up by and moved with it. By this construction, the bolt shell 2.8 iszclosed anditslocki'ng arms 32 are fully seated in the pockets 21 before' the key 45 is. operatively positioned and in the unlocking or rearward stroke of the actuator 33, the actuator moves' a' predetermined distance before the key 45 is picked up to enable the locking arms 32 to be cammed out of their pockets 21. It will be apparent from Fig. 2 that the mutually engageablecamporticns 35 and cam pockets 2l' are suchas to provide for the absorption by the receiver 20 of rearwardthrust on the bolt shell 28 with a minimum inward camming action on the locking arms 32. It will be apparent, that, when the irearm is discharged', only a smalll part of the gas pressure on the head of the bolt shellv 28 is transmitted against the key shoulders 43' but preferably as shown in the drawings, the

shoulders 45 and the ledges 31 present substantially parallel surfaces, when the bolt shell 2.8 is locked to the receiver 20, thereby to minimize frictional resistance to the rearward movement of the key 45. (See Fig. 2.)

The bolt shell 28 carries aI suitable extractor. While the extractor may beY of any desired type, that shown in the drawings is simple in construction and has proved satisfactory in use. I provide the bolt shell 28 with a peripheral groove 4l' adjacent itshead and having a channel 48 in communication with' the face 29. The bolt shell, as may be seen in Fig. 4, has at surfaced portions 49 inthe groove 41 inclined towards each other to. receive. the resilient clip 5|) which isA formed integrally with the extractor 5| which extends forwardly in the channel 48 and is exposed in the recessed face 29 to engage with and grip the rim of'.V the cartridge 24 seated in the barrel chamber thereby to pull it there from when the bolt moves towards its open position.

As illustrative of means to eject an extracted cartridge o r case through the receiver port 25, I have shown (see Fig. 8) av support 52 in the receiver 2&1' below the path of the bolt 23. On the support is pivotally mounted aY U-shaped member 53 of resilientA stock disposed to yieldably engage the bolt shell. 28 and to entera slot 54 inV its bottom portionthereby tov be engaged by an extracted cartridge orv case as the bolt 23 movesA into v its openA position to dislodge it from theextractor 5 and eject it through the port 25.

In practice, I provide a firing pin having a rear portionv 55 of greater cross sectional area than itsfront. portion` 56` thereby to provide an intermediateshoulder 51. The rear part of the actuator 38 has` an axial bore 58'to slidably support the pin portion 55, and its-front part and the bolt shell 28 each have an axial bore 59 slidably receiving the pin portion 53, and the keyv l5A has a boredimensioned to receive the pin and to provide a shoulder 63 engageable by the pin shoulder 51. While the pin portion 55 is slidably connected to theactuator 38 for short movement relative-thereto by the transverse pin 6| engageablewith the extremities of the recess 62, the shoulder 53 inthey key 45 prevents the firing pin from being operatively positioned until the key 45p0sitively supports the locking arms 32 in the receiver pockets 21. By this construction, the ring pin serves to hold the bolt shell, the key in the actuator together enabling the bolt to be quickly and easily assembled or taken apart.

Before describing the firing mechanism, it is convenient to consider the bolt operating means. While the actuator 38 may be moved forwardly and rearwardly to lock and unlock the bolt shell 28 to the receiver 20 manually or by other means, I have shown it as operated by gas pressure.

To accomplish this, I provide a slide consisting of a pair of members 63 interconnected. at their rear ends by an upwardly disposed loop 64 seated in the recess 44 on the actuator extension 43 and including contact shoulders 65 adjacent its lower end. The loop 64 holds the pin 6l in place so that the bolt 23 is held against disassembly until the loop 64 is disconnected therefrom. The members 63 extend forwardly below the barrel 2| but in parallel with its axis and have their front ends interconnected as at 66. The slide part 66 is apertured to receive the rod 61 seated against the downwardly disposed receiver post 68. A spring 69 locked as at 10 to the rod 61 and supported thereby engages the slide part 66 yieldably urging it forwardly into a position in which the bolt 23 is closed.

The stock 22 includes a fore part 1|, commonly called the fore stock, and is chambered as at 12 to receive the bolt operating slide and is slotted as at 13 so that a portion of one of the members 63 of the slide is exposed and to it I secure a charging handle 14 by which the bolt 2| may be manually operated against the action of the spring 69. The slot 13 is of suicient length to accommodate the handle 14 as the bolt 2| reciprocates between its open and closed positions. The handle 14 has a pair of spaced dovetailed lugs 15 (see Fig. 12) and is recessed to receive the lock 16 which has an arm 11 resiliently urging its locking head 18 outwardly adjacent one of the lugs 15 and its operating arm 19 into a position in which its is easily engaged. The portion' of the member 63 to which the handle is to be attached has a pair of openings 80 spacedto receive the lugs 15 and including beveled extensions 8| which lock the lugs when slid therein as will be apparent from Figs. 1l and 12. When the handle is locked to the member 63, the locking head 18 blocks one of the openings 80 so that sliding movement of the handle 14 relative to the member 63 is impossible unless the operating arm 19 is pressed to retract the locking head into the handle 14. (See Fig. 2.)

While the bolt 23 may be variously operated, either automatically or manually, I have shown it in Fig. 1 as unlocked by gas pressure. To accomplish this result, I secure a cylinder 82 to the barrel 2| with a port 83 eifecting communication between them. Within the cylinder 82 is a piston 84 having one end 85 of reduced diameter and normally seated against one end of the cylinder 82. The other piston end 86 is also of reduced diameter and extends through the sealing f" plug 81.

At 88, I have shown a tappet which is slidably seated on the exposed end 86 of the piston and is bored to slidably receive the rod 61 and to have predetermined limited movement relative thereto. A spring 89 supported by the rod 61 yieldably maintains the tappet 88 in spaced relation thereto and urges the piston 84 forwardly in its cylinder 82. `By this construction, the piston -84 has a relatively short stroke and through the tappet 88 exerts sufficient power on the slide to c'arry'the actuator 38rearwardly to unlock the bolt shell 28. Because of the relative movement between the actuator 38 and the key 45, the unlocking of the bolt shell 28 is timed so that' the gas pressures in the barrel 2| are safe to employ in ensuring or continuing the movement of the bolt 23 into its open position.

This construction also has the advantage that it provides for ease in assembly or disassembly of a firearm in accordance with my invention. It will be noted that the rear end of the receiver 20 is closed by a threaded cap 90 recessed to receive the buffer spring 9| engageable by the bolt when in its open position. Adjacent to but forwardly of the cap 90, I form the receiver 20 with a recess 92 in its upper part dimensioned to'enable the slide loop 64 to be raised out of the recess 44 on the actuator extension 43 thereby to disconnect the bolt 23 from the operating slide.

Because of the tappet connection between the piston 84 and the rod 61, the rod 61 is held suf-- ficiently rigidly to prevent such lifting of they slide until the tappet 88 has been fully seated against the rod 61 and the piston 84 is in contact with the front wall of the cylinder 82. The rod 61 may then be lifted from its seat in the post 68. In order to prevent the tappet 88 from lbecoming lost, it is slidably pinned to the rod 61 as at 93.

In Fig. 1, I have shown trigger controlled firing mechanism which is Well adapted for use in semi-automatic operation of a firearm and which 'can be readily converted to full automatic op- I accomplish this result by providing the receiver -cap 90 with one and preferably two depending arms 98 adapted to receive the upright 95 between them and having a tongue and groove interlock 99. The vertical groove 91 is adapted to receive the receiver post 68 and the groove A-91 and post 68 have a tongue and groove interlock |00. The interlocks 99 and |00 present surfaces that are substantially in parallel with the axis of the barrel 2| so that the firing mechyanism may be slid forwardly relative to the receiver and connected thereto. As will be apparent from the drawings, the slidable interlock 99 is of sufficiently greater length than the interlock |00 to enable the former to become partially established ahead of the entry of the post 68 into the groove 91.

When the firing mechanism is thus connected to the receiver 20, it is positively locked thereto by means of a bolt |0| extending through the arms 98 of the cap 90 and the upright 95 and the bolt |0I is, in practice, the means locking the receiver and firing mechanism to the stock 22. (See Fig. 5.) l

Particularly, when a firearm is to be used for military purposes, it is provided with a hand guard |02 which ts over the barrel 2l forwardly of the receiver 20 and engages the fore stock 1| to which it is connected by a removable clip |03.

In accordance with my invention, I form the hand guard |02 to fit loosely over the barrel 2| that the barrel: 21V a loose fit therein-L junctiorr of' theareceive1205- and the'. barrel 2| establishes a shoulder |04. having an arcuateV recessV andi adjacent: thereto: the/.barrel has..

a rearwardly disposedshoulderf |06.' (see'Fig; 13.)

by'the'clip: |03, the spring element or elements are tensioned against the barrell2l.. This' not. only' results lina supportfforfthe barrelI 2 |vv that does not depend on accurate inlettingl and .isnot subject to swellingzor-warpingtof theV wood,-4 but also ensures: cooler. operation; becauseof; the'- otherwise loose fit of the barrel in the hand guard'.

andV forestock;

For maximum convenience; Igprefer. to useA a clip |93 ofthe typeshown' in Fig. l5y and made from resilient stock. A loop1|||l fora sling` (not shown) includes a pair ofiparallel arms ||'2 and. H3. The arm ||2y ispivotally connectcdto the free end |'|'4` ofthe-clip |'l|3f,y the other free end of which includes an-` outward'curveA ||5z I pivotally-secure a cam |16, having-anoperating'lever to the arm ||3. The cam HS engages with the curve. ||3vand as theY canris` rocked' passed center; the free ends of' the-clip |03are` drawn together andY the' cam H6'v placed underxsuitable locking tension. Preferably, the hand` guard |02 and the fore stock'll are recessed to establish a barrel receiving groove^ ||8.

The :firing mechanism shown inthe drawings consists of `aihamme'r |I9v-pivota-ll'y mounted on the' baseV plate94r to swing fromu a positionV engaging the rear end: of the-.firing pin when: the bolt 23 is-closed androcked4 rearwardly" into a cocked position. byA rearwardA movement of.' the bolt travellingintoits openwposition. The forked end |'2 ofv an actuator'rod |2|2` is pivotally connected to thehammer'l1'9 while itsl free end is slidably supported in avblock. |22 having `a shoulder |23Y engageableby the sea-r |24 adjacent' the free end ofthe rod' thereby 'to vhold 'the .hammer ||9 in its cocked position. Av firing spring |25' Supported by the'rod" |2| engages the forked endv thereby to drive the'hammer 9yforwardlywh'en the Sear is disengagedY from its' shoulder; A' spring |26 anchored Ato the plate 94'- ensures' engagement of the scary withi its shoulder during operation'.

Pivotally conne-ctedto theplater-SG' is a trigger- |22 shown asprotected-bythe trigger guard |28;

safety while it is recessed as at |3550 that in its .second position.. the rod |.2| may be lifted to re-V lease'its sear. This type of safety is satisfactory because it is positive, conveniently located, and easily operated. In practice, the member |33 is threaded-at one end to receive a nut |35 and eX- tendsthrough the stock 22 so that its extremities are exposed on. both sides thereof but countersunk with-.reference tothe surfaces thereof.

Thel trigger guard |28 is locked at its rear end to the plateV 94' by thebolt |31 which also serves to anchor the-spring. |26 in place while its front end is slidably connected thereto as at |38 and it and the magazine 26 are formed with complemental interlocking portions |39 to hold the magazine securely inplace. The trigger guard |28 is'suiliciently resilient so thatit'may be engaged in the zone |40 to enable the interlocking portionsv to bedisengaged thereby providing a safe magazinerelease.

The firing mechanism just described may be rendered' fully automatic as shown in Figs. 16-18. I pivotally mount on the plate 94 an arm |4| disposedV to be swung rearwardly to force the pawl arm |32' back outof the path of the rod |2|. Mounted on the pivot support for the hammer |9 is a U-shaped member |42.having its closed end presentinga shoulder |43 engageable by the pawl arm-|32 when held back by the arm I4| so that the rear end ofthe member |42 is lifted when thel trigger is pulled. Pivotally connected to the member |42 intermediate its ends is a second U-shaped member |44 having its closed end |45v rearwardlyv of the block |22 and below its shoulder |23 and its free ends |45 extendingvforwardly and upwardly and terminating normally just below the path of the contact shoulders as the bolt 23 reciprocates. now pulled to lift the member |42, the second member |44 is also raised sufciently so that its free ends |45 are in the path of the contact shoulders 65 to be engaged thereby to rock the second memberto lift its closed end |45 to release the sear so that so long as the trigger is held back, the firearm functions automatically.

From the foregoing, it will be apparent that firearms in accordance with my invention have many important features and advantages. The most important of these relate to the bolt as they ensure simplicity of construction, ease of operation, and a positive lock of the bolt in its closed position that is easily established and easily released regardless of the bolt operating means used in conjunction therewith.

What I therefore claim and desire to secure by` Letters Patent is:

1. In a rearm, a barrel having a chamber, a receiver having an ejection port and a cam pocket, andA a bolt in said receiver reciprocable between a closed position in which it seats a cartridge in said chamber and an open position rearwardly of said port, said bolt comprising a shell having at one end a cartridge engaging face, an actuator slidable with reference to said shell, anda locking arm pivotally connected to said shell and including an outer.

cam portion substantially complementalin size.

tending to wedge it outwardly, and a key includngvv a shoulder and being slidable with When the trigger is` reference to said shell into andY out of a position in which its shoulder is engageable by the freeend of said arm to lock said arm in said pocket. said key also being slidable with reference to said actuator to provide predetermined movement in either direction of the latter before the former is moved.

2. In a rearm, abarrel having a chamber, a receiver having an ejection port and a pair of transversely alined cam pockets, and a bolt in saidy receiver reciprocable between a closed cartridge seating position and an open position rearwardly of said port, said bolt comprising a shell, locking arms-pivotally connected to said shell to swing from an inoperative position in which said shell is free to reciprocate into an outer position and being located so that they may enter said pockets when the bolt shell is in its closed position, an actuator movable forwardly relative to said shell to engage said arms thereby to drive said bolt shell forwardly and to wedge them apart when said bolt shell is closed and means slidable relative to said bolt shell to block inward movement of said arms, said means being slidably connected to said actuator to move into and out of arm blocking position in-lagging relation to said actuator.

3. In a firearm, a barrel having a chamber,

a receiver having an ejection port and a pair 9 of transversely alined cam pockets, and a bolt in said receiver reciprocable between a closed position in which it seats a cartridge in said chamber and an open position rearwardly of said port, said bolt comprising a shell having at one end a cartridge engaging face, an axial chamber opening through its other end, and a transverse slot intersecting said chamber, and a pair of locking arms, a pivotal connection between each arm and said shell, each of said arms including an outer cam portion substantially complemental in size and shape to said pockets, an inner contact portion, and a ledge spaced rearwardly thereof, said arms being housed in opposite ends of said slot to have an inoperative position therein in which said bolt shell is free to reciprocate and being located so that when said bolt shell is in its closed position each of said arms may be pivoted outwardly and into one of said receiver pockets to lock said bolt vshell against rearward movement, an actuator including a portion slidably extending into said bolt shell chamber and having a transverse slot and a Wedge engageable with said contact portions thereby to urge said arms outwardly, and a key interconnecting said bolt shell and said actuator through their transverse slots, said key including shoulders and being slidable with reference to said bolt shell into and out of position in which said shoulders are engageable by said ledges to lock said arms in their operative position, said key also being slidable with reference to said actuator thereby to provide predetermined movement in either direction of the latter before the former is moved.

4. The rearm of claim 3 in which the mutually contacting surfaces of the shoulders and the ledges are substantially in parallel when the locking arms are in the receiver pockets.

5. The :rearm of claim 3 in which each pivotal connection consists of a tapered pintle integral with each arm and a tapered pintle receiving bore intersecting the shell slot ends adjacent their front extremities.

6. In a firearm, a barrel having a chamber,

a receiver having a port and a pair of transversely alined cam pockets, a bolt in said receiver reciprocable between a closed position in which it seats a cartridge in said chamber andan open position rearwardly of said port, anda firing pin having its front portion of lesser cross sectional area than its rear portion and establishing a shoulder, `said bolt comprising a shell having at one end a cartridge engaging face, an axial chamber opening through its other end, and a transverse slot intersecting said chamber, and a pair of locking arms, each of said varms including an outer cam portion substantially complemental in size and shape to said pockets, an innerwedge, and a ledge spaced rearwardly thereof, said arms being pivotally connected to said -bolt shell and housedv in opposite ends` of said slot to have an inoperative position therein in which said bolt rshell is free to reciprocate and being located so that when said bolt shell is in its closed position each of said arms may be pivoted outwardly and into one of said pockets to lock said bolt shell, an actuator including a portion extending into said bolt shell chamber and having a transverse slot and a wedge contacting surface, and a key interconnecting said bolt shell and said actuator through their transverse slots, said keyv including shoulders and being slidable with reference to said bolt shell into and out of a position in which said shoulders are engageable by said ledges to lock said arms in Vtheir operative position, said key also being slidable with reference to said actuator thereby to provide predetermined movement of the latter before the former is moved, said shell, said actuator having bores to slidably receive the front and rear portions of said ring pin respectively, means connecting said pin to said actuator for limited ,sliding movement relative thereto, and said key having a pin passage therethrough dimensioned to receive saidpin and establishing a seat engageable by its shoulder so that said actuator and said key are connected to said shell and said'flring pin isprevented from becoming operative until said locking arms are operatively positioned.

7. In a firearm, a barrel having a chamber, a receiver having an ejection port and a pocket, and a bolt in said receiver reciprocable between a closed position in which it seats a cartridge in said chamber and an open position rearwardly of said port, said bolt comprising a shell having at one end a cartridge engaging face, an actuator slidable with reference to said shell, a locking arm, a pivot connecting said arm to said shell and including a portion to enter said pocket to lock the bolt against rearward movement and located to swing outwardly into said pocket when the bolt shell is in its closed position or inwardly into a position in which said bolt shell is free to reciprocate, said arm and said pocket also including mutually engageable cam portions tending to swing said arm inwardly when said bolt shell is urged rearwardly, said actuator engaging said arm rearwardly of but adjacent to said pivot to drive said shell forwardly and tending to wedge said arm outwardly, and a key including a shoulder and being slidable with reference to said shell into and out of a position in which its shoulder is engageable by the free end of said arm to lock said arm in said pocket against being cammed inwardly, said key also being slidable with reference to said actuator and being engaged thereby on predetermined movement in either direction of the latter before the former 1I iS movedv into or outof itslocking position there.- byv to providemeans to enable force applied to saidvv bolt urging ittowards its open, position to be delayed before it causes, said arm to be cammed inwardly.

8. In aiirearm, a barrel havingI a chamber, a receiverl having an ejection port andv a cam pocket, and a bolt in said receiverl reciprocable between a. closed position in which it seats a cartridgepin said chamber' and an open position i rearwardly of, said port, said bolt comprising a shell. having at one en d a cartridge engaging face, an actuator slidable withreference to said shell,V alockingarm,apivot connectingsaid arm tosaidslfiell,` said arm includingV an outer earn portion to enter SaidA pocket and boing located to swing outwardly, into said pocket when the bolt shellis in its closed position or inwardly intoaposition in` whichl said bolt shell isV free toreciprocate,A said actuatorY engaging said4 arm rearwardly ofl but adjacent to Asaid pivot to drive Saidhell: forwardly; andtending to wedge said armV outwardly,- and a key including a shouldery andbeingvv slidablewithl reference tol said shell into and out ofvapositionin which its shoulder is engageableby thefreeend of saidarm to .lock said arinin saidpocketl against being cammed inwardly, sajdkeyl alsobeing slidable with referene; to saidl actuator and being engagedand moved A therebyonA predetermined movement in either direction of the actuator.

9; Ina firearrilf,v abarrelhaving a chamber, a receiver having an ejection port and a pocket, and a bolt insaidlreceiver reciprocable between a closed position in Whichit seats a cartridge in f said,` chamber and anfopen position rearwardly ofnsaidport, said bolt. comprising ashell having at one .end a cartridge engaging face, an actuator slidable with reference. to said` shell, a locking arm pivotally connected to said shell and including anv outer portion to enter.v said pocket tolock-the bolt against rearward movement and located to swing outwardly into said pocket when the. bolt shell .isin its closed position or. inwardly into a. position in whichsaid bolt shell is free to reciprocate, said arm and said pocket also including mutually'engageable cam portions tending to swing, saidarm .inwardly whenv said vbolt shell is .urged rearwardly, saidv actuator engaging Y said'arm and tending-to wedge. it outwardly and a` keyy including a. shoulder and being; slidable.

with reference.- to said. shell into i and out of a position inY which its.v shoulder. is. engageable by lil the fr eeend of said arm to.` loclgsaidi-arrninsaid pocket against being; camrned4 inwardly. .Said-key also being slidablewithv reference to.saidactu ator to provide predetermined` movement; in eitherdirection of` the latter before the former is moved.

10. In a firearm, a barrel.nai-'ving a chamb er aj receiver having an ejection port and a pain` of transversely alined cam pockets-,ay and arzholtrin said receiver reciprocable between. a,close.dfcar. tridge seatingposition and.anzopentpositionfrear; wardly of` said port, said' bol-t, comprisingashelh locking arms pivotally connected, toSaidfshell,y to swing from an inoperativefpositionz in whichgsaid shellis free to reciprocateinto.zanouterhcsiti0i and being located so thatihey.. may; entergsaid pocketswhen the bolt shell; isin its ;closed. pesi# tion, bolt actuating, means-,includingga forwardly and rearwardly,y reciprocable.` para an; aotuaton part having limited forward:A and; rearwaldrmove: ment relative to saidy shell,` and inv itsvv forward; movement engaging Said: arms: therebrf to,4v drive saidbolt shell forwardlyandto wedgezsaid arms, apart; when said-bolt shell is closed,.andfmea ns toY block said armsagainst; inward; movement;

whensaid armsare in their*i blocking: gpQSition,

said means having limited. forwardgandi rear..- ward movement relative to said shell and touneP of said parts tolagbehind said;lastnamedinart on' rearward movement'tthereot HQWARDTR'... CLARKE. j

REFERENCES-GITED? l The following references are off recordf--in the'- fiie of this patent:

UNITED STATES..