US2942523A - Charging devices for a firearm - Google Patents

Description

June 28, 1.960

Filed June 18, 1953 4 Sheets-Sheet 1 :m m s m r V u mn N i 0m) FQ/ QQQ www m5, NQ Q s@ n ,A7/SQ? S w m NNY A, ,r Y nl EB Q QQ M S 8 @Q w. QQ 1 .QH/Q NQNII R |r QQ r ,l R R l lw@ Uma, L# WQ l lilmm; NQS Il! -ww wmHf, L Q1 Il l v .fw I.. l 1| QQ\\ @fmm I .v Ilm .HTH

June 28, 1960 B. DARslE 2,942,523

CHARGING DEVICES FOR A FIREARM Filed June 18, 1953 4 Sheets-Sheet 2 INVENTOR. I

Burns Il i1-rs1@ BY A T'TENE YS 4 Sheets-Sheet 3 Filed June 18. 1953 E wm 2 N a 15 m u EN d w \m\ QQ @w l m 1% III NM )k QQ w@ Q QN @m In: .QQ NQ IIIH l.. G Il i. V (A. Q\ PQ I uvl mM t! ArraeNE Ys United tates Patented June 2d, 196i) '2,942,523 n VvCHARGING Deviens 'non ArnznAnM l Filed 111.11? ,18, ,1953, Ser.- No 334,764

-16 claims. (ci. fsa-1) The `present inventionrelates vto automatic firearms and more particularly gto firearm chargingftlevices.n Y

The present inventionis primarily concerned With'gun lhargers for `machneglnis or .the like having Ya reciprocat- 'mg member, such as a bolt, that reciprocates between a battery and recoil position. 'i I In charging firearms such as machine of large Yca1iber-it isrst necessary Vto retract the bolt from the battery position to insert the rst cartridgefin the cham- Yber to start tiring. The normal reciprocation of a bolt ina rearmis actuated by the tiring of a cartridge. However, to load the firearm with each new lstring of cartridges, the bolt must be retracted and it is preferred to use an automatic charging device for operation, thereby eliminating the necessity of theU gunner using manual means.

In certain installations i where several firearms Aare grouped together in conined 'quarters of a vehicle or plane, 1t is necessary to operate such firearms at adistantfpoint due to such confined quarters.' A i It is therefore an object of thisinvention to provide a charging device whichmayfbe efficiently operated from a distant .point with remote control for charging. a iirearm.

Another objectof .thisinvention is 'to provide .a simple, vrugged and inexpensive charging device for an automatic firearm.

Another object of thisinvention is Ato provide a charger with a minimum `number of parts of light weight andflikely to require very little if any'faftention as far as repairs are concerned, as no vsprings Aare used ltov actuate the device disclosed herein.

A further object of this invention is to provide, n cuhargi ing action of the bolt that naturally decreased the cyclic rate, of the firearm. Y

Another very important object of this invention resides in thecylinder and piston arrangement which provides a Ygreater force on the charger nut to 'retract the bolt to the recoil position than is provided to move 4the bolt into the battery position. c

Stillanother very important objectofthis invention resides in the double acting screw and nut mechanism op- `rerated bylluid pressure in such a manner that the travel of the charger nut is nearly twice the travel of the piston which operates suchcharger.

The specific nature ofthe invention as well as other objects and advantages thereof will clearly appear from `a vdescription of a preferred embodiment as'shown in the accompanying drawings in which:

Eig. l showsv a .partial sectionalized longitudinal |view with the rbolt inthe recoil position;

lFig. 2,is a similar view of Fig. 'l with .the bolt in the battery position;

Fig. 3 is a rear end view showing the relation of the chargers with the bolt; t v

Fig. v 4 isa schematic view showing the means for supplying the air in the recoil and counter-recoil action of .the

charger cylinders;

Fig. 5 is a bottom perspective view of .the bolt .showing ythe lbolt lugs and latches therein;

Fig. 6 is a front end viewof the bridge; and

-Figure 7 is a section to an enlarged scale taken along lines 7-7 of Figure 6 and showing the chargers in relation tothe receiver, an intermediate part .being 'broken away. I

Referring to the drawings, reference numbers .12., 14 and y16 designate the receiver, charger assemblyleft hand andcharger assembly right hand,'r.espectively. v*Reference numeral 18 designates -a bolt assembly that is mounted in receiver l2 for reciprocating'movements .between a bat-tery and recoil position and that does not require the `use of Vdriving springsA to .return the lbolt vtothe battery position, depending instead .upon the Vimpact force on 'thejbuler mechanism, whereby `the reboundreturns sand assembly to the battery position. f

Bolt lassembly 18, onthe extreme rear end, .-iseprovidml with a pair of'downwardly depending chargerlugsjZll from ving `device constructed jin 'such 'almanner fhati does not ehangejthe outside 4corlnguration' 4ofthe rearni Lstrucwrany. e

vA particular'obj'ect ofthis invention isto vprovide"c lonble `action screw means for `moving'theFboIt Afrom a battery to ja recoil position and viceversa.' f

- Another Aparticular object o'f invention is to provide a pneumatic Idevicet'hat is exceedingly compact :and is of vsuch shape andsize'that 'it canfbe vreadily assembled inside the receiver in such a .manner'jthat it does :not inter- 'fere with and/or function with "the operatingpartsfwhile such parts are reciprocating .in thereceiverjduring the of a .device lthat will hold the bolt/in KAa retracted orlecoil Vposition and also will .holdsuch bolt .battery .position.

An important object of .thisinvention permits .the .assembling of two synchronizedpneumatic or hydraulic charging devices on the inside of the receiver, one on each Aside thereof to cooperate lwithv4 downwardly :depend- Vthe bottom thereof, spaced an equal distance apart from Ythe ongitudinal ,central {line vof such assembly. YBolt assembly 18, forwardly of 'lugs '2.0, is provided y,a pair of slots 22 positioned longitudinally Vparallel with charger lugs 20. c Each slot 22 is arranged to pivotally receive aspring-'biased latch assembly 24 fora pnrpose .to be described later. Bolt assembly' 18 ,provided on .the left side thereof with an electrical -contact 26 arranged to propel a conventional tiring pinforwardly :to discharge a cartridge when energizedby an electrical source (not shown).

Receiver 1Z-is of'iU-shaped .structure having ,a bottom p late 2S and upwardly extending .plate portions `3A) and 32 on -theleft and righthand side thereof, respectively. Receiver-12 f isalso providedwitha cover 'V3.4 having down- `wardly depending side plates .on .the left :and right hand Yside thereof, designated by the numerals 36,and'3,fre

. spectively, that are secured `to plates 30 and 32, respectively. Receiver '1 2 is provided .with a-lower butler bracket 40 extending upwardly fromthe-jbottorn plate -28 inthe center thereof `and longitudinally positioned therein. Iapproximate vcylindrical-bore t2 fis .provided on each :side of lower buifer fbracket .40 longitudinally .disposed and constructed -toreceive oneo'f ythe charger " assemblies 14 or 116 vin Atheir .respective positions.

Vertically above .each of bores .42, there is :provideda .longitudinally disposed shelf ,44;having`vertical and horizontal planar fsurfacesg-at right angles :to veach iother, ...ar-

ranged to slidably receive bolt assembly 18. ReceiverA 12 is also provided with an upper buffer bracket 46 longitudinally disposed vertically above lower buffer bracket 40 and having a bottom surface constructed to complete in cooperation with shelves 44 an oblong opening 52, substantially large enough to permit the -reciprocation of the bolt assembly 18 therein. Receiver 12 is also provided, on the left side of opening 52, with a longitudinally disposed recess 54 to permit the passage of contact 26 therethrough, while bolt assembly 18 is reciprocating from a battery to a recoil position and vice versa.

A pneumatic or hydraulic charger valve assembly 48 is secured to plate 32 on the right hand side of receiver i 12 and is operated by a conventional solenoid 50 for controlling the air or oil impulses for the functioning of charger assemblies 14 and :16 that will be described in more detail later. The preferred embodiment as disclosed herein will hereafter refer to the pneumatic charger valve assembly only with the'userof airfas a medium for functioningthe chargers. A charger bridge 56 is secured to the lower front end of receiver 12 and is provided with a pair of spaced-apart cylindrical recesses 58 in alignment with bores 42 of receiver 12 and being of approximately equal diameter as bores 42.

Charger assembly 16, located on the right side of receiver 12, comprises basically a tubular charger cylinder 60, an outer piston 64 and an inner piston 66. Tubular charger cylinder 60, right hand, is of such diametrical proportions as to be received in bore 42 of receiver 12 and the front end of said cylinder is fixedly secured in recess 58 of charger bridge 56. Cylinder 60 is provided with an elongated slot 62, extending from the rear end to approximately half the entire length in the upper part thereof, the center line of which is positioned on the left side of the longitudinal center line of such cylinder.

Inner piston 66, used in both charger assemblies 14 and =16, is provided with a reduced front end 74, iixedly secured in a bore 68 of bridge 56, aligned with and forwardly of each recess 58, and an enlarged rear end or head 70 arranged to slidably engage in outer piston 64. Outer piston 64 is provided with a longitudinal bore 72 for'cooperation with head 70 of piston 66. Piston 64 is provided with a reduced bore 78 on the front end thereof, communicating with bore 72 and arranged to slidably receive an intermediate portion 76 between head 70and end 74 of piston 66. An interiorannular groove 166 is positioned in bore 78 and is arranged to receive a ring packing 168. Piston 64 also hasian exterior annular Y groove 170 positioned radially from'groove 166 and arranged to receive a ring packing 172. Head 70 of piston 66'is provided with an annular'groove 80, around the outer periphery thereof, to receive` a ring packing 82. An air sealing plug 84 is threadably secured in the rear end of bore 72 of piston64." Piston 64 is provided with Yan offset upstanding bracket 86, projecting upwardly through cylinder slot 62 andhhaving Va bore 88 in the' upper part thereof, arrangedto receive a ball bearing 90. Approximately vertically abovethe cylindrical recess 58, on the right hand side of bridge 56, and horizontally aligned with bore 88 of bracket 86, a hole 92 is provided to receive a reduced end portion 94 of an inner screw "96. End portion 94 is xedly secured in hole 92 through the medium of a pin 98. Inner screw 96 is provided with left hand threads 100 on the exterior thereof to cooperate with interior threads 102 provided on an outer screw- 104, that is rotatably mounted thereon. Outer screw'104 is provided with a plug 106 inthe rear end'thereof that is fixedly secured to ball bearing 90 for rotation therewith. A charger"nut 10.8, having right` hand threads 182, is threadably mounted on outer screw 104 which is also provided with right hand threads 184 whereby rotation of screw 104 traverses nut 108 therealong. Charger nut 108 is provided with an upwardly extending lug 160 on -the left side thereof for cooperation with lug 20 and latch 4 assembly 24 on the right side of bolt assembly 18 for a purpose to be described later.

Charger assembly 14, located on the left side of receiver 12, is similar in structure and elements to charger assembly 16, but with the following exception.y Tubular charger cylinder 110, left hand, is identical with charger 60, except that the slot 112 inthe upper part thereof, is positioned on the right side of the longitudinal center line of such cylinder. Outer piston 114 is provided with an offset upstanding bracket 116, projectingupwardly through cylinder slot 112, of tubular charger cylinder 110 and is provided with a -bore 88 in the upper part thereof. Charger bridge 56 is provided with a hole 118, located approximately above cylindrical recess 58 on the left side of such bridge and being in alignment with bore 88 located in bracket 116, such hole being arranged to receive end 94 of inner screw 96. A charger nut 162 is threadably mounted on outer screw '104 of charger assembly 14 for traversing therealong and is provided with an upstanding lug 164 on the right side thereof for cooperation with lug 20 and latch assembly 24 on the left side of bolt assembly 18 for a purpose to be described later.

Charger valve assembly 481s designed with a valve mechanism (not shown as it does not form a part of this invention) thatis actuated by a solenoid 50, whereby a high pressure air' impulse is either permitted to enter the recoil side of the system through orifice 120 or the counter-recoil side through orifice 122 as selected, both being located inthe right side plate portion 32. Orifice 120 connects with a downwardly depending passage 124 that is joined at right anglesy by a recoil duct '126 leading forwardly therefrom and terminates in charger bridge 56. Grifice 122 connects with a downwardly depending passage 128 that is joined at right angles with a counter- ,recoil duct 130 leading forwardly therefrom parallel with Y .orice 138 positioned directly in front of head 70. Piston 66 is also provided with a longitudinally disposed exhaust conduit ,140, juxtaposed to channel 136, leading from the rear end and terminating in a radially disposed Vhole 142 positioned at the junction of intermediate portion 76 and end 74.

Recoil duct 126 connects with `a tunnel 144 in charger bridge 56 that terminates in a cavity 146 rearwardly of each bore 68 and leading into recess 58. The forward .ends of ` cylinders 60 and 110 are provided with a disc 148V having a cylindrical bore 150 therethrough to receive end 74 of piston 66. Disc 148 is provided with a series of angularly disposed holes l152, in relation to the horizontal center line,"for the admittance of high pressure air impulses therethrough. Forwardly of disc 148, cylinders `60 and 110 are provided with a series of radially disposed, holes 154 leading outwardly 4from the interior thereof, arranged to allow'the exhausting of air pressure therefrom on the counter-recoil cycle. -Forwardly of disc 148 and within the interior of cylinder 60 there is assembled on end 74, a check valve assembly 156'V provided to allow air pressure to pass through angular holes 152 that is in turn impinged against a forward end 158 of outer pistons `64 or 114 for actuating such pistons to the recoil position.

. Operation To withdraw bolt assembly 18 from the battery po'- isition in charging the gun, solenoid 50 actuates the valve "antenas l into tunnel 1Min charger -'bridge 16. 'The :air impulse opens the valve assembly 156 bythe actionuof the air against such assembly and rthen passes through 'holes 5152 and against ends 158 'of router pistons 64 and V1:14

thereby actuating such pistons to ythe recoil position. When valve-assembly 156 'is .being opened, .it moves rearwardly thereby blocking off holes 154 as Vshown in Fig. l thus vpreventing 'the escapement of air to atmosphere. During the recoil movement of said pistons, a portion of the'air enters hole 142 passing through conduit 144) and impinges upon the forward surface of plug 84, thereby applying -an additional .pressure to move said pistons rearwardly providing a greater force than the force ap- .plied during counter-recoil. The trappedair between .head 70 of inner piston '66 and the inner front Wa-ll n longitudinal bore "72 of piston 64 is permitted to escape through orice 138 through channel 136 and out Yhole .134 into the counterrecoil side of thesystem to exhaust Ainto Athe atmosphere.

To return the bolt to the battery position, the 'solenoid aotuates the valve mechanism 'in such 1a manner as to exhaust air from passage 120 and to permit air to 'enter the counter-recoil side ofthe system passing through ori- Viice'fllZ-Z., passage 128, 'duct i3!) 'and Tinto "tunnel '132 in charger bridge '5"6. "The 'air 'then passes through hole 134 lalong channel 136 andiou't orifice '138 VTandysuch yair Vthen impinges upon a wall 174 inthe forward part-of longitudinal bore 72, thereby forcing piston "64 forwardly 'to the "battely position with a lesser force than farpplied during recoil. The trapped air -between a Arear lend izf of ,piston 66 and a 'forward end 173 'of plug 84 is -ex`i hausted 'through conduit llitt) and out hole 142. This trapped air vthen passes out Y'through holes 1'52`a'c'tuat'in-g valve 156 'forwardly .thereby closing same and permitting the `trapped .air to Vescape through 'holes 1154. YThe `trapped Vair between 'the forward end 1'58 of pist-on 64 and the rear faceld of disc 148, also escapes through "holes 132, thereby assisting the actuation of valve A1556 for- Wa'rdly .in cylinders 60 and 111) and `the residual air .passes through holes 154.

.From the foregoing, vit'will be 'apparent to one 'Skilled in th'e art 'that 'herein is disclosedja simple-compactedev'ice 'for charging a jfirearm 'that will hold Vthe zbolt in a recoil 4position 'and 'also assist in holding such bolt in 'the battery position. v

While the `form 'of Aembodiment 'of the invention herein disclosed constitutes `a preferred form, it is understood that other forms `might lbe adapted as may 'come within the scope of 'the claims which follow.

I claim:

yl. vIn aiirearm, `a receiver, a bolt'reciprocablyvinountedforlrnovement between a battery `and recoil position in said receiver, a pair :of charger cylinders mounted inside said receiver, an inner pistonxedly secured in each of said cylinders in the forward 'endthereoi 'a tubular piston slidably mounted over "each 'of said linner pistons' and operable between 'a Lbattery .and `recoil position in .'said cylinders, and means movablysecuredto each of vsaid tubular `pistons for 'moving-said boltto 'a battery'or recoil position.

2. In a firearm, 'a receiverga boltreciprocably mounted for movement between a battery and recoil position in'said receiver, a pair of charger cylinders mounted inside'said receiver, an `innerpiston ixedlyzsecured -in each of said `cylinders -in the forwardend thereof, a tubular Vpis/.ton slidably mounted over `eachv .of Ysaid inner `pistonal-means .associated with each tof said inner 'pistons and tubular pistons 'for ymoving Ysaid :tubular Apistons .to ,a :battery ior .recoilposition in said cylinders, land means V .movably secured :to each Aof kysaid `tubular pistons for .-moving -saidibolt [to a battery 4or recoil position.

1n-7.a.iirearm, 'a receiver, a vbolt .reciprocablymount- V `ed for .movement .between a .battery .and Yrecoil 7position in .said receiver, .a .pair lof @charger cylinders .Amounted inside said receiver, an inner` piston xedly secured Vin each nof said cylinders in the forward end thereof, J'a tubular vpiston slidably mounted over "each of said inner pistons, means"associated with each of :saidfinner pistons andt'ubular pistons Afor moving said tubular pistons to a battery or recoil position in said cylinders, lscrew meansV associated with each l0f said tubular pistons and -movl able therewith, `and means movably secured to Veach of said -screw means for 4moving `said bolt to a'battery or recoil position. Y t

4. In a viirear-m, a 'receiver 'having Va 'pair vof *spacedapart 'longitudinally Adisposed holes on the yinside thereof, a bolt reciprocabiy mounted Vjfor movement Vbetween 'a battery 'and lrecoil position in said receiver, a bridge 'xedly ksecuredinthe front end'of said receiver and being provided recesses 'longitudinally 'aligned Lwith said hotes in said receiver, Isaid bridge being lprovided with a bore *forwardly 'of each of 'said recesses Yand aligned therewith, a 'charger cylinder xmounted 'in Aeach Iof :said holes 'and secured ron the front end thereof insaicl recess of said vbridge, an inner piston having a reduced front end Yportion tlixedlysecured lin each of -s'a'id bores of vsaid bridge, a tubular piston 'slidably'mounted over each of v 5. The combination de'ned in claim l4 wherein said.

'screw means comprises an inner vscrew jiixed-ly 'secured on the forward Aend 7thereof in said bridge and I`having screw :threads 'on the exterior thereof, `an outer screw 'rotatably mounted Aon said inner 'screw and being rotatably secured -o'n the rear end thereof to said tubular piston, 'said .outer screw having threads 'on the interior there'offor cooperation `with said threads on said linner screw and having threads on the exterior thereof 'for`mov- .ing said )last-'mentioned means therealong vwhereby said 'bolt maybe moved to abattery 'or a recoil position.

Y 6. *In :a l'iirearrrn a 'receiver "having ia pair of 'spacedapart longitudinally disposed holes on -vthe "inside thereof, a `bolt reciprocably mounted Afor movement between 'a 'battery and recoil position in said receiver, 'abridge fixedly secured '1in the front end of'saidreceiver and lbeing providedwith recesses :longitudinally 'aligned with 'said holes in said receiver, said bridge being provided with a bore 'forwardly 'of eacfh of sa'id recesses and aligned therewith, a charger cylinder mounted jin 'each offsaid holes of .said receiver 'and securedonlthe front endthereof in said're'cess of 'said bridge, atubu'larpiston slidably mounted in '.each of said cylinders, lan inner piston having a reduced front end portion iixedly 'secured 4vin each of said bores of said bridge, .said ,inner piston :being `provided with an intermediate portion rearwardly of -said :front end Vand anfenlar'ged head portion okn'the rear jend thereof arranged to slidably receive saidtubnl'ar piston Ythereon, a reduced' bore being 'provided in the 'forward end of said tubular piston'arranged'for slidable engagement with lsaid intermediate portion of'said 'inner piston, means associated with each of `said rinner fpis'tons and 'tubular lpistons for movingsaid .tubular l.pistons to a battery or recoil position, screw .means associated'with'each of said tubularpistons and movable therewith, and means movably secured .to each rof jsa'id screw means r"for .moving said bolt to a' battery or recoil position.

`7, In a rearm', va re'ceiverhaving `a of `spacedapart longitudinally disposed lholes on the .inside thereof, a Abo'lt reciprocably mounted for movement -b'e'tween a battery and 'recoil position in saidreceivenwa jbri'dge viixedly secured Vinfthe front end of said .,:rec'eiver vand beng providedwth recesses with reduced bo'resf'leading forwardly therefrom and longitudinally,alignedwithsaid Yholes A.in said receiven` ,a charger cylinder mounted l:in each of saidl holes o'f said receiver and "secured on the front end thereof in said recess of said bridge, each of said cylinders being provided with a rearwardly extending slot in the upper part thereof, a tubular piston slidably mounted-in each of said cylinders and `havingA an upwardly Aextending bracket receivable in said slot having a bearing rotatably mounted in the upper part thereof, said tubular pistons being provided with a reduced bore in the front end rand a plug threadably secured in the rear end thereof, an inner piston having a reduced front end portion xedly secured in each of said bores, said inner piston having 'an enlarged head portion on the rear end thereof receivable in saidtubular'piston and an intermediate portion receivable in said 'reduced bore, an inner screw fixedly secured to said bridge approximately above each of said cylinders, a rotatable louter screw ixedly secured to said bearing of said bracket and being threadably mounted on saidinner screw for movement therealong, a nut threadably mounted on leach of said outer screws and havingan upwardly extending lug portion, means. associated with each of said innner pistons and tubular pistons for moving said tubular pistons to a battery or recoil position whereby saidV movement of said tubular pistons moves said nuts therealong, and means associated with said bolt cooperating with said lugs of said nuts for moving said bolt to a battery or 25 recoil position. l

8. In a firearm, a receiver, a bolt reciprocably mounted for movement between a battery and recoil position in lsaid receiver, a solenoid controlled source of air pressure mounted on the inside of said receiver, a pair 3 of chargers mounted inside said receiver, a rst passage means connecting said source of air pressure with said chargers whereby said chargers are movedy to a recoil position, a second passage means connecting said source ,means movably secured to each of said screw means for moving said bolt to a battery or recoil position.

9. The combination defined in claim 8 wherein said screw means comprises an inner screw xedly secured on the forward end thereof in said bridge and having screw threads on the exterior thereof, an outer screw rotatably mounted on said innertscrew and being rotatably secured on the rear end thereof to said tubular piston, said outer screw having threads on the interior thereof, for cooperation with said threads on said inner screw and having threads `on the exterior thereof for moving said lastmentioned means therealong whereby said boltV may be moved to a battery or a recoil position.Y

10. ln a iirearm, a receiver, a bolt reciprocably mounted in said receiver, a solenoid controlled source off air pressure mounted on the inside of said receiver, a bridge xedly secured in the front end of said receiver, a pair of charger cylinders mounted inside said receiver, an inner piston fixedly secured in each of said cylinders in the forward end thereof, a tubular piston slidably mounted over each of said inner pistons for movement between a recoil and battery position in said cylinder, a rst passage means in said receiver and said bridge connecting said source of air-pressure Vwith-` said cylinders, each of said cylinders being providedwith a pressure operated valve in the front end thereof constructed to admit air pressure therethrough whereby said air pressure impinging on said tubular piston moves said tubular'pistonfto a recoil position, a second passage means in said receiver and said bridgeV connecting said source of air pressure with a forwardly extending tunnel in said inner pistons whereby said air pressure impinging on `said tubular pistons moves said tubular pistons to a battery position, screw means associated with each of saidtubular pistons and A movable therewith, and means movably secured 'to said screw means for moving said bolt to a battery or recoil position. t

11. charger means for reciprocating a slidable bolt in a firearm receiver, irst screw means lixedly secured in the receiver, second screw means threadably engage-y able on said first screw means, fixed means on the charger means for rotatably securing said second screw means 6 thereto, third screw means threadably engageable on said second screw means` and adapted to move therealong in response to the rotation of the latter, means `engaging said third screw means with the bolt, and means for longitudinally reciprocating the charger means to impart 10 corresponding movement to said second screw means tive to the travel of the charger means by a distance substantially equivalent to the length of said second screw means.

12. In charger means for reciprocating a slidable bolt in a rearm receiver, a tubular charger piston slidably mounted in the receiver parallel to the bolt, a xed screw of air pressure with said chargers whereby said chargers 3 secured at the front end thereof in the forward end of the receiver, a hollow screw having an interiorly threaded portion engageable with said fixed screw, bracket means onsaid tubular piston for rotatably securing said hollow screw thereto in threadable engagement with said fixed screw, a nut threadably mounted on said hollow screw Afor longitudinal movement therealong in response to rotation of the latter, said nut having a radially projecting lug engageable with the bolt, and means for longitudinally reciprocating said tubular piston to impart corresponding movement to said hollow screw along said xed screw whereby the threaded engagement therebetween simultaneously rotates said hollow screw to move said nut therealong and thereby increase the extent of travel of the bolt relative to the travel of said tubular piston by a distance substantially equivalent to the length of said hollow screw.

13; In charger means for reciprocating a slidable bolt in a rearm receiver, a pair of hollow cylinders lixedly 40 disposed in ether side ofthe receiver below and parallel `to the bolt, a tubular piston slidably disposed in each of said hollow cylinders, an inner screw xedly mounted at the front end thereof in the forward end of the receiver between the bolt and each of said tubular pistons, an

offset bracket iixedly secured to the rear end of each of said tubular pistons, a hollow outer screw having an exteriorly threaded portion and an interiorly threaded portion engageable with each of said iixed inner screws and having a rearwardly projecting portion journaled in said offset bracket, a nut threadably mounted on each of said 4hollow screws for longitudinal movement therealong in response to rotation of the latter, each of said nutshaving a lug projecting radially therefrom in engagement with the underside of the bolt, said inner screws and said interiorly threaded portions of said hollow outer screws having mating left hand threads, said nuts and said exteriorly threaded portions of said hollow outer screws having mating right hand threads, and means for simultaneously reciprocating said tubular pistons in said hollow cylinders to impart corresponding movement to said hol- `low outer screws along said xed inner screws whereby the engagement of said right hand threads therebetween simultaneously rotates said hollow screws to move said nuts therealong by means of the engagement of said left 55 hand threads therebetween and thereby increase the extent of travel of the bolt relative to the travel of each of Vsaidtubular pistons by an amount substantially equivalent to the length of 'each of said hollow screws.

14. In a firearm having a receiver and a bolt slidably mounted therein for reciprocal movement between battery and recoil positions, charger means for reciprocating the bolt comprising in combination, a hollow cylinder iixedly mounted in the receiver parallel to the bolt `and extending rearwardly to terminate adjacent the rear end of the receiver, a tubular piston slidably mounted in said cylinder for reciprocal movement therein, an inner piston iixedly mounted at the front end thereof in the forward end of the receiver to extend rearwardly into said hollow cylinder and into the hollow interior of said tubular piston, said inner piston having an enlarged head portion at the rear end thereof cooperating with said tubular piston to limit movement thereof in either direction to an amount substantially half of the length of said hollow cylinder, an inner screw having left hand threads on the exterior periphery thereof and iixedly secured at the front end thereof adjacent the front end of said hollow cylinder to extend rearwardly between the bolt and said tubular piston parallel thereto, a hollow outer screw having left hand threads on the interior periphery thereof for mating engagement with said left hand threads on said inner screw and having right hand threads on the exterior periphery thereof, a bracket projecting radially from the rear end of said tubular piston for connecting said outer screw thereto, said bracket having a bearing portion therein for rotatably engaging the rear end of said outer screw, a nut having right hand threads engageable with said threaded exterior periphery of said outer screw for longitudinal movement therealong in response to rotation of the latter, a radially disposed lug on said nut for effecting non-rotatable engagement thereof with the bolt, a uid pressure means lfor reciprocating said tubular piston to reciprocate said outer screw iointly therewith, said left hand threads on said inner screw and within the interior periphery of said outer screw being arranged to impart rotation to the latter during the reciprocating movement thereof, said right hand threads on the exterior periphery of said outer screw and within said nut being arranged to effect relative movement therebetween simultaneously with the longitudinal movement of said outer screw relative to said inner screw whereby the total travel of the bolt is substantially equivalent to the travel of said outer screw on said inner screw plus the travel of said nut on said outer screw.

l5. In charger means for a irearm having a receiver and a bolt slidably mounted therein for reciprocal movement between battery and recoil positions, the combination of a hollow cylinder xedly mounted in the receiver parallel to the bolt, an inner piston having an elongated body portion iixedly secured at the forward end thereof in the front end of the receiver and extending rearwardly in said hollow cylinder to terminate in an enlarged head portion, a tubular piston slidably mounted in said hollow cylinder and having a closed rear end and a reduced bore section at the front end thereof for slidably receiving said elongated body portion of said inner piston therethrough whereby said enlarged head portion is in slidable engagement with the interior periphery of said tubular piston,

means connecting said tubular piston to the bolt, said inner piston having a first channel therein terminating in an exit adjacent the front face of said enlarged head portion and a second channel opening between the interiors of said hollow cylinder and said tubular piston, a source of uid pressure medium connected to the forward end of said hollow cylinder and to the forward end of said second channel in said inner piston, means for directing said uid pressure medium through said hollow cylinder and against the front face of said reduced bore section of said tubular piston to impart rearward movement thereto for retracting the bolt to recoil position, said first channel and said inner piston being arranged to admit a portion of said uid pressure medium into the interior of said tubular piston and against said closed rear end thereof for increasing the rearward force imparted thereto, solenoid means for blocking access to said hollow cylinder and simultaneously uncovering access to said second channel in said inner piston, and means for directing said fluid pressure medium into said tubular piston between the rear face of said reduced lbore section therein and the front face of said enlarged head portion to reverse the travel of said tubular piston for returning the bolt to battery position whereby the lesser pressure area of the rear face of said reduced bore section in comparison to the pressure area on the front face thereof requires a correspondingly lesser amount of fluid pressure to return the bolt to battery position than that required for retraction thereof to recoil position.

16.`The combination defined in claim 15 including` valve means slidably disposed for limited reciprocal movement in the forward end of said hollow cylinder for controlling the entry of uid pressure medium therein, and a plurality of radially disposed exhaust ports in the front end of said hollow cylinder opening into the path of rearward movement imparted to said valve means during the passage of uid pressure medium therethrough upon recoil of the bolt whereby said exhaust ports are operative only during return movement of the bolt toward battery position. A

References Cited in the fle of this patent UNITED STATES PATENTS 1,942,189 Shepard Ian. 2, 1934 2,373,385 Davie Apr. 10, 1945 2,413,416 Ostlund et al Dec. 31, 1946 2,423,446 Grant July 8, 1947 2,472,002 Clark May 31, 1949 FOREIGN PATENTS 713,123 Germany Oct. 31, 1941 914,885 France July 1, 1946

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