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Publication numberUS2457835 A
Publication typeGrant
Publication dateJan 4, 1949
Filing dateDec 5, 1945
Priority dateDec 5, 1945
Publication numberUS 2457835 A, US 2457835A, US-A-2457835, US2457835 A, US2457835A
InventorsSigmund Schiff
Original AssigneeSigmund Schiff
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Gun bolt
US 2457835 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

2 'sheets-sheet 1 S. vSGHIFF GUN BOLT Jan. 4, 1949.

Filed Dec. 5, 1945 q irnun Y p w -Humm Jan. 4, 1949. S, sci-"FF 2,457,835

. GUN BOLT Filed Deo. 5, 1945 2 sheets-sheet 2 FigzL Patented Jan. 4, 1949 T OIF F I CE' GUN BOLT Sigmund-Schiff, Cincinnati, Ohio Application December 5, 1945; lSerialNo 633,031A

(Cl. 89"-1910l (Granted under the. act of: March. 3',v 1883,. as'

5 Claims.'

amendedl April 30, 1928; 370 O'. G.

The invention described herein may be manufactured and used byV or for the Government-ttor governmental purposes without the payments to me of any royalty thereon.

This invention relates struction of bolt for use automaticguns. Y A

It is the primary object of'v this invention'` to provide' anv improved construction ofA bolt for use` with" the above mentirm'ed*typeI gun and which' 1s of a greatly simplified construction and design as compare'd'to the boltl now'employed' in thel 20 mm. gun; and by means of which many of the parts of the conventional bolt are eliminated to thus provide a bolt which is more`- eillcientfv and to an improved` conwi-tli 20mm. aircraft' faster in operation; andv whichv is considerably more' durable through the elimination' of` many small parts which are especially'subje'ct to break-.-

ofY the type operated .byv a combination of forces including gas recoil means and'blowbackwmeans; which is formed of twoprimary sections having a limitedV relative movement for unlockingy the bolt after firing to permit recoilof the-bolt with accompanying, extraction', ejection andfeeding of the ammunition; and which is providedE with novel means` which, upon counter-recoil movement, initially 'locks onesection of the boltin bat'- tery position' and thereafter permits forwardv movement of another section of the bolt-forproj'ecting theiring pin to explode the chambered round torcau'se the cycle'of operation oftliecpiec'e to be repeated;

Other objects andadvantages'of the-invention'v willhereinafter'become-more fully apparent from thefollowing description of the' drawings, which illustrates a preferred-embodiment of. the inven-y tion, andwherein:

Figure 11 isa fragmentary longitudinal sec*-v tionalvievv, partlyfin side elevation, ofz'afportion: cfa' 20 mm'.l aircraft gun and with theiinprovedboltl shown locked; therein in battery4` position;

Figure 2 is a similarview shovvingtheA bolt held in a-retracted", cocked position;

Figure .':Yis a view'similarto Figure 1 showing theinitial movement of one section` ofthe bolt, relatively' to the other section thereof, andrconstitutingthe rst stage of the bolt recoil; and

Figure 4'and-5`are.cross sectionallviews on enlarged scales taken substantially along. the planes as indicatedby the linesA II-fland-- respectively, .ofrEigure l..

Referring more particularly to* the drawings. wherein like reference. characters`- designate likev or,v correspondingy parts throughout thel several viewa, (i4 designates: generally, a. portioni ofy the'y More particularly, itis an object ofthe invengtion to" provide an improved*construction'offbolt.

ory the: M2;v series. which: is of: conventionaln con struction` except for the belt, designated generally- 1, andwhich comprises the invention.

` Only sormuch'of" the receiver'and other associated parts have been illustratedas are necessary-tofillustrate the'application ofthe bolt 1;

The bolt 1, as'previously'mentioned; is actuated in recoil-initially by a gas operated'pis-ton and thereafterv by blovvba'ck force. The piston, not shown, obtains impetus from' a portion of the propelling gasesV from the'bore 8 of the barrel 9 throughy a port, not* shown, to drive a: sleeve Ill rearwardly; Sleeve' I0 is* connected at its forward end to the piston. Thel rear endof the sleeves IIl is shown'in FigureV l, and said rear end" 6 lengthwisefthereof. The forward ends of pushi rods lllprotrudfrom lthe forward end of' re' ceive'r 6 into the pathof rearward movement of the yoke; Thefsleeve' Il!V is thereafter returned to a'forvvard; inoperative `position by an extension springVV III.

The bolt Iincludes-ay lowerse'c'tion or breechblock, designated' generally I2, and` an upper section -v orf' breechblock slide, designated generally I3; As -best seerriri Figures 4 and'5, there-v ceiver 6 is provided with an upper chamber I4 in which the bolt l isfreciprocally mounted and the lower portion ofi' the receiver 6 is provided withf rails |52 for slidably` supporting' the bolt 'IL The! upper surface of" the breechlock I 2 is provided With recessed faces I6 at the sides thereof, andthe undersideof the breechblock slide I3 is provided with depending sides` or shoulders Il for engaging" the faces' I6 and for providing a connection. betWeen-tliefbolt' sections I2 and I3 tov permit' relative A lengthwise sliding movement,

but which prevent l any lateral movement of? the connectedisections'.v Axially'fof the bolt 1; thesechtions` I z 'andi |73; areizprovidedwith complementary recessesi which extendffrom adjacent the forward endof' the bolt'I" arrctwlrif'zl'i` open outwardly of the rearend-thereof'to form' a bore' I8 in' which arflrin'ge'pln' I9=ls slidably mounted lengthwiseof the bolt 1.1

Aslfbe'stseen iii-FigureA 1, a driving-spring guideplun'gerf 20; formed. of .telescoping sections, has one endthe'reof extending through the bore I8v and terminating in the head 2I which bearsk against; the rear`end of the firing pin I The' opposite end of the guidepl-unger 20, not shown,- :bears against the' buffer assembly, not shown, and

likewise is provided withr a headed end. Thev` guide .plunger 201 carriesa.r driving or counter# recoil spring' 22; the en'dsiofwliich bear against I1 form the lower portions.

ceiver 6. As best seen in Figure `l, firing pin I3A is provided with a body portion which is circular in cross section and which is stepped intermedia-te of its ends to form a forwardly facing shoul-` der 23 which bears against a rearwardly facing shoulder 24 on the breechblock vslide I3. The

breechblock I2, at its forward end, is provided K with an upstand'ing wall 2'5 the forward side of 4 with the forwardly facing inclined faces 50 at their rear ends which coact with the rearwardly facing correspondingly inclined faces 5I of the 'extensions 41, as will hereinafter be described,

A The lock 4I is recessed in its underside to forro "a latch face 52 to engage a Sear 53, in a conventionalv manner, whenvvthe bolt 'I is in a fully retracted position, as :seen in Figure v2. The lock v4I which forms the bolt face and which is provided with an axially arranged opening 21 to receive tained in the chamber 29 of' the rifle bore 3. The

rear side of wall 2E forms an abutment for an annular forwardly facing shoulder formed by the tapered part 28, and against which the firing pin bears when bolt I is in battery position, as seen in Figure l. The bolt 1 is provided withan extractor 30', carried by the breechblock vI2 vin av conventional manner. *f The breechblockslide I3, as seenin Figures 4 and 5, is provided with corresponding vertically enlarged side portions 30, of which the shoulders diate of the ends of the slidev I3, are provided with downwardly and outwardly opening recesses 3| through each of which extend a guide rod 32; The guide rods 32 are suitablyv anchored at their ends in portions of Athe slide I3 and mount expansionsprings v33 which are carried thereby. A lug 34 is slidably mounted on each of the guide rrods 32.

against the forward ends of the lugs 34 for urging said lugs rearwardly. A plate 35 is secured to each side of the slide I3 by screw fastenings 35, and said plates are provided with inturned lower ends, as seen in Figure 4,'which vcombine with portions of the perpendicular parts of the plates 35 to form housings for inclosing the rods 32 and the springs 33. As seen in Figure l, .the inturned portions of the plates 35 are cut out, at the rear ends thereof, to form openings 31 through which i project the depending extensions 38 of the Vlugs 34. The sides of the breechblock I2 are provided with upwardly opening notches 39 `to receivethe extensions 38 for yieldably connecting the-bolt sections I2 and I3. 1

The breechblock I2, adjacent its rear end, and at the bottom thereof, is provided with a rearwardly facing shoulder having a rearwardly directed arcuately shaped groove 40 which extends transversely thereof. A breechblock lock 4I is mounted in the recessed underside 42 'of the' I2, behind the rearwardli7 facingv breechblock shoulder, and is provided with a rounded forward end 43 which is pivotally mounted in the recess 4I). The receiver 6 is provided with a transverse-` ly disposed, fixed breechblock key 44 having an upwardly and forwardly facing, ytransversely extending notch 45 to receive the lower, rear end of the breechblock lock 4I, when the breechblock I2 is in a battery position, ras seen in Figure 1. The slide I3, adjacent its rear end, is provided with downwardly opening notches 45, at the sides thereof, .to receive the upwardly and forwardly inclined projections 41 which project from ythe lock 4I, adjacent the side edges thereof. The notches 46 are provided with rearwardly facing upwardly and forwardly inclined cam faces 48, at their for-9 ward ends for engagement with the upwardly Aand forwardly inclined forward faces 49 of the extensions 41, and the notches 46 are also provided Sides 30, interme.- v

The rear ends of the springs 33 bear y;

is also provided with forwardly facing upwardly and rearwardly inclined cam surfaces 54, at the sides thereof, for engagement with the cam sur faces which are rigidly secured to the sides of the receiver Ii, as vbest illustrated in Figure 2. The forwardly facing, upwardly yextending side of the notch 45 is inclined rearwardly to provide a cam engagement with the similarly inclined rear end portion 56 of the lock 4 I. s

The side portions 30 extend `to the forward end ofr the breechblock slide I3 and are disposed just behind and at the sidesof the breechblock por tion 2j6 with the forward ends thereof exposed, to be engaged by pushrods Illa which are reciprocally mounted in the receiver 3 and which are en f gaged in a vconventional manner by the yoke of by the extractor 30.

v the sleeve I0. y

, Assuming the bolt 1 to be in its battery position, as seen in Figure l, which position it assumes at ther instant that the firing pin I9 strikes and explodes a round'of ammunition, not shown, contained in the chamber 23 and which rbears against the face of the bolt l; as the projectile fromthe'round rof ammunition moves through the bore 8 a portion of the propelling gases thereu of acts uponv the piston., not shown, connected to the sleeve` I0, for driving the sleeve rearwardly. This rearward movement of the sleeve i0 .is im-r parted, through its yoke and the push rods IIJa to the forwardv ends of the side rails 3U against which the rear ends, not shown, of push rods Illa bear.l The side rails 30, forming integral parts of the breechblock slide I3, upon receiving the impact of the push rods IIla cause the slide I3 to be driven rearwardly. The breechblock I2 is held in a battery position due to the lock 4I engaging the notch 45 of the breechblock key 44, thus causing the slide I3 to move relatively to the breechblock I2. The shoulder 24 of slide I3 engaging the shoulder 23 carries the ring pin I9 rearwardly with the slide I3 and relatively to the breechblock I2, as illustrated in Figure 3, thus retracting the firing pin extension 28 out of the opening 21 and out of engagement with the cartridge case, not shown, held against the bolt face This initial, gas produced movement of the slide I3, relatively to the breechblock I2, causes the cam surfaces 43 to engage the cam surfaces 49, as seen in Figure 3, to cam the lock 4I upwardly and out of engagee .-i ment with the notch 45 and partially into the notches 46, so that .the lock 4I clears theuppersurface of thebreechblock key 44. This unlocks the breechblock I2 permitting it to be driven rearwardly by blowback pressure and also locks"l the slide I3 in its retracted position to the breechblock I2. As the bolt 1 moves rearwardly against the action of the spring 22, the lock 4I is supported in its elevated position of Figure 2 by the rear sections of the rails I5. The tubular "rear end portion 51 of the bolt V1 strikes the movement of the'bolt 11, therim of the cartridge.

buffer plate, not shown, to terminate the recoil travel of the bolt after which the driving spring 22 begins to propel the bolt 1 forwardly in its counterrecoil movement. Midway of the recoil seen in Figure 2; in

chamber 29 by the extractor 30 is engaged by the horns of the ejector, one of which is shown at 58, for ejecting the empty cartridge case through the bottom of the receiver 3 in a conventional manner. If the trigger, not shown, has

face during the recoil movement of the bolt l, and will thereafter have moved upwardly and into the recessed underside of the lock 4| to latch the bolt 7 in an open and cocked position, as which position it will be held until the trigger is again pulled to release the sear 53 from engagement with the forwardly facing shoulder 52 of lock 4l. Normally, however, the trigger is held retracted to thereby hold the reaches the battery position, as seen in Figure 3, the rear end of the lock 4| clears the upper surface of the breechblock key 44, allowing the rear end of the lock 4| to be cammed back into the notch 45 by the cam surfaces 54 of lock 4| engaging the cam surfaces 55 of the receiver 6, to force the lock 4| downwardly and to thereby release the slide |3 to move forward relatively to the breechblock l2. The breechblock slide 3 is thereafter driven forward, relatively to the breechblock |2, and to its forwardmost position of Figure 1 by the driving spring 22 and the springs 33, through the engagement of the extensions 38 with the notches 39, to thereby project the extension 28 of the firing pin I9 through the opening 21 for exploding the newly chambered round of ammunition and to cause the cycle of operation, which has been previously described, to be repeated.

Various modiiications and struction of the bolt, forming the invention, are

the invention as hereinafter dened by the appended claims, as only a' preferred embodiment thereof has been illustrated and described.

I claim:

1. In an automatic weapon, the combination of a receiver, a breechblock reciprocally mounted therein, a breechblock slide reciprocally mounted on said breechblock, a ring pin, said breechblock and said breechblock slide having opposed complementary recesses forming a bore for receiving the firing pin for longitudinal movement therein, said breechblock slide having a limited longitudinal sliding movement relative to the breechblock, a key connected to said receiver, a lock on said breechblock adapted to engage said key for holding the breechblock in battery position, gas actuated means for moving the breechblock slide rearwardly relatively to breechblock, cam means on the lock and breechblock slide for camming the lock out of engagement with said key when the breechblock slide is moved rearwardly relatively to the breechblock, said breechblock being movable rearwardly by blowback for extracting an empty cartridge case, driving means for movthe breechblock and breechblock slide forward to pick up and chamber a round of ammunition, cam means on the breechblock slide and lock for returning the lock to a locked position with said key when the breechblock reaches a battery position, to release the slide, and said driving means bearing against the firing pin to move the breechblockJ slide forward, relatively to the breechblock, to project the ring pin to detonate the chambered round of ammuntion.

2. A bolt as in claim 1, said breechblock slide being disposed above the breechblock, and said breechblock having an upwardly extending forward end forming the bolt face and provided with an opening for the firing pin.

3. A gun bolt comprising a breechblock forming the lower section of the bolt, an upstanding wall on said breechblock and provided with an opening, a breechblock slide forming the upper section of the bolt, means attached to said breechblock slide for moving the same rearwardly, and spring means connecting the breechblock and breechblock slide for limited lengthwise sliding movement of the breechblock slide relatively to the breechblock, said breechblock and breechblock slide having complementary recesses forming a bore, a spring projected firing pin contained in the bore and adapted to be projected through the opening in said upstanding wall, and engaging shoulders on the breechblock slide and firing pin for retracting the firing pin from the opening when the breechblock slide is moved rearwardly relatively to the breechblock.

4. A gun bolt as in claim 3, and a breechblock lock pivotally mounted on the breechblock, a breechblock key xedly disposed relatively to the bolt and engaged by the breechblock lock for retaining the breechblock in battery position, interengaging cam means on the breechblock slide and breechblock lock for camming the lock away from the key to a released position when the breechblock slide is moved rearwardly relatively to the breechblock.

5. A gun bolt formed of an upper section the said sections having opposed complementary longitudinally extending recesses forming a bore extending longitudinally of the bolt, and a lower section, a ring pin slidably mounted between said sections and lengthwise thereof in said bore, a counterrecoil spring means bearing against the ring pin and urging it forward, relatively to the bolt, said upper section being mounted on said lower section for limited reciprocating movementv relatively to the lower section, said firing pin and upper section having engaging faces to cause the firing pin to move rearward with the upper section and to cause the upper section to move forward with the firing pin, means for initially moving the upper section rearwardly relatively to the lower section, for cooking the firing pin, and means for latching the upper section and the lower section in a rearward position.


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


Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1572450 *May 15, 1919Feb 9, 1926Marlin Firearms CorpAutomatic rifle
US2093169 *Mar 1, 1934Sep 14, 1937Firm Ceskoslovenska ZbrojovkaAutomatic firearm, in particular machine gun
US2098727 *Jul 6, 1936Nov 9, 1937Johannes Lahti AimoLock mechanism for automatic guns
US2267501 *Jul 7, 1939Dec 23, 1941Ceskoslovenska Zbrojovka A SAutomatic firearm
US2361985 *Apr 24, 1940Nov 7, 1944Marc BirkigtAbsorbing means especially for firearms
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2816484 *Aug 27, 1951Dec 17, 1957Grages Richard RAutomatic firearm of the blow back type
US6722255 *Nov 21, 2002Apr 20, 2004Geoffrey A. HerringApparatus and method for actuating a bolt carrier group of a receiver assembly
US7610844 *Sep 19, 2005Nov 3, 2009Colt Defense LlcFirearm having an indirect gas operating system
US7934447 *Nov 2, 2009May 3, 2011Colt Defense LlcFirearm having an indirect gas operating system
US8176837Oct 11, 2010May 15, 2012Jason Stewart JacksonFirearm operating rod
US8453364Oct 9, 2007Jun 4, 2013Colt Defense LlcFirearm having a removable hand guard
US8528458Jul 27, 2011Sep 10, 2013Bernard T. WindauerPressure-regulating gas block
US8640598Jul 16, 2011Feb 4, 2014Jason Stewart JacksonSleeve piston for actuating a firearm bolt carrier
US8919025Jun 3, 2013Dec 30, 2014Colt's Manufacturing Company LlcFirearm having a removable hand guard
US8943948May 3, 2011Feb 3, 2015Colt's Manufacturing Company LlcFirearm having an indirect gas operating system
US9228799Dec 29, 2014Jan 5, 2016Colt's Manufacturing Company LlcFirearm having a removable hand guard
US9261314Feb 3, 2014Feb 16, 2016Jason Stewart JacksonSleeve piston for actuating a firearm bolt carrier
US9719739Feb 5, 2015Aug 1, 2017Bernard (Bernie) T. WindauerGas block balancing piston for auto-loading firearm
US20030126781 *Nov 21, 2002Jul 10, 2003Herring Geoffrey A.Apparatus and method for actuating a bolt carrier group of a receiver assembly
US20060065112 *Sep 19, 2005Mar 30, 2006Grzegorz KuczynkoFirearm having an indirect gas operating system
US20100095834 *Nov 2, 2009Apr 22, 2010Colt Defense, LlcFirearm having an indirect gas operating system
WO2006137874A3 *Sep 19, 2005Jun 14, 2007Colt Defense LlcFirearm having an indirect gas operating system
U.S. Classification89/152, 89/190, 42/16, 89/191.1
International ClassificationF41A19/00, F41A19/30, F41A3/40, F41A3/00
Cooperative ClassificationF41A3/40, F41A19/30
European ClassificationF41A3/40, F41A19/30