US2397963A - Automatic firearm - Google Patents

Description

pril ww HARVEY AUTOMATIC FIREARM Filed Oct. l5, 1942 2 Sheets-Sheet l 3mm Earle MQI-ia'rva AWM @9 3946 E. M. HARVEY 2,397,963

AUTOMATI C FIREARM Filed Oct. l5, 1942 2 Sheets-Sheet 2 E g 2% 2/5 4/.5 432s go Ela Eff-E 125.1412 M .Har Vey melgmmw Patented Apr. 9, 1946 AUTOMATIC FIREARM Earle M. Harvey, Springfield, Mass.

Application October 15, 1942, Serial No. 462,185

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, Without the payment to me of any royalty thereon.

This invention relates to improvements rimer actuated Iirearms.

Automatic iirearms which are operated by a force derived from the primer of a cartridge have been known in the art, In firearms of this type, the primer of a cartridge is permitted to be forced backward a slight distance out of the cartridge, thereby imparting a hammer-like blow to the bolt, which force is utilized to secure automatic operation. However, such type of rearm has not achieved any general success due to its failure to obtain consistent operation.

It is an object of this invention to provide an improved form of primer-operated gun.

It is a particular object of this invention to produce an improved bolt construction for a primer-operated gun which is light in weight, has a minimum number of parts and may be readily assembled or disassembled.

The specic nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a partial longitudinal sectional view of a firearm embodying this invention showing the bolt in the recoiled position.

Fig. 2 is a View similar to that shown in Fig. 1 but with the bolt shown in the forward position,

Fig. 3 is an enlarged partial longitudinal sectional view taken on a horizontal plane through the axis of the rearm shown in Fig. 2 of the bolt and the chamber portion of the barrel show ing the inertia member in the bolt and the construction of the cartridge case in the chamber.

Fig. 4 is an enlarged sectional view of the bolt taken on the line 4 4 of Fig. 3.

Fig. 5 is an enlarged partial longitudinal sectional view of the bolt taken on the line 5--5 of Fig. 9.

Fig. 6 is an enlarged view of the bolt operating cam taken on the line 6 6 of Fig. 3 showing the locking lug in the normal position prior to discharge of a cartridge.

Fig. 7 is a view similar to that shown in Figl 6 but with the locking lug shown shortly after the discharge of a cartridge.

Fig. 8 is a top elevational view of the cartridge extractor.

application above referred to.

Fig. 9 is a front end elevational view of the bolt.

Fig. 10 is a cross sectional view taken along the plane IIJ-l0 of Fig. 1.

In Figs. 1 and 2 there is shown in assembled relation a preferred form of primer-operated firearm to be operated by the setback of the primer of a cartridge. While the firearm shown preferably utilizes a cartridge of the Atype disclosed in my co-pending application of even date herewith, Serial Number 462,186, any other cartridge having a primer that will be displaced rearwardly upon its discharge may also be utilized.

Such a rearm comprises a stock Ill of conven tional construction, a receiver 20 and a conventional barrel 30 secured to the forward end of the receiver as by the threads 30a, The chamber 3| of the barrel is likewise of conventional shape and of suitable dimensions to receive a cartridge l. Cartridges I are fed into the firearm by means of a box-type magazine Il, conventionally mounted in the receiver and having a spring follower I2.

In the top of the receiver a bolt 40 is mounted for reciprocal movement. Locking of the bolt in battery position is accomplished by two oppositely disposed integral locking lugs 4ta and 4Ib (Fig. 3). Lugs 4|a and Mb engage appropriate shoulders Zia and 2` Ib respectively within the receiver by rotation of the bolt when it is brought into battery position. The mounting of the bolt and the placement and operation of the locking lugs preferably embodies the construction shown and described in U. S. Patent No. 1,892,141 to John C. Garand. Extending axially through the center of the bolt (Fig. 3) is a ring pin 42 mounted so as to permit limited axial movement of the pin within the bolt. Actuation of the ring pin is accomplished by a trigger 33, sear 315, and hammer 35 arrangement (Figs. 1 and 2) similar to that shown in the forementioned patent to John C. Garand.

The front portion of the bolt 4i] however is substantially modified. In place of the Usual solid construction, the entire front portion of the bolt is composed of two intertting pieces, comprising the main bolt member 40 and an inserted portion 43. This insert 43 fits loosely in the front portion of the bolt around the firing pin 42 and is capable of slight movement along the axis of the bolt. In frontal area, the insert 43 is of such extent as to cover a primer 6 and a bushing 5 in the head of the cartridge l when utilizing cartridges of the type disclosed in my :zo-pending When any other cartridge is utilized the area of the insert is such as to cover the primer. The insert 43 has on one side a radially extending portion 43a which extends into a correspondingly shaped recess or slot in the bolt locking lug 4|a extending through the forward and rear faces of the lug. Likewise on the opposite side of the insert, radial extension 43h projects into a corresponding slot in the bolt. Rearward movement of the insertv member 43 within the bolt however is limited bythe rear of the insert striking the adjacent solid portion of the bolt 40.

An operating rod 50 is mounted for reciprocal movement along the side of the receiver 20. The rod l50 is provided with a dovetailed tongue (not shown) which engages a dovetailed slot (not shown) provided on the side of the receiver 20. The operating rod is provided with a handle 5| for manual operation thereof. On the inner side of the rod adjacent the handle 5| there is provided a recess '52 into which thebolt locking lug 4|a, extends. This recess is L-shaped in conguration (Figs. 6 and 7 so that as the operating rod 50 is moved rearwardly from the position shown in Fig. 6 to that shown in Fig. 7, the locking lug 4|a is cammed by the walls of the recess 52 in such a manner as to rotate the bolt, unlocking the locking lugs 4|a and 4|b from the receiver shoulders 2|a and 2lb respectively and permitting the bolt to be retracted. As was previously mentioned, the locking lug 4|a has a 1ongitudinal slot therein receiving the extension 43a of insert 43 and the extension thereby extends also into the recess 52. Thus in the battery position of the bolt 49, as shown in Fig. 3, any rearward movement of the insert member 43 will be transmitted by the extending arm 43d to the operating rod 50.

The operating rod 50 projects beyond the front `end of receiver into the region between the lforward end of spring 55 abuts against the rear of inertia member 53. A spring guide rod 56 is also secured to inertia member 53 extending reara recess 43d provided in the bolt insert 43. The

ejector 10 is thus held in place by the insert 43 but limited axial movement of the ejector is possible. In battery position insert 43 is held against the base of the chambered cartridge by force of operating spring 55 operating throughy wall ofl recess 52 and portion 43a of insert 43. In the event insert 43 should not be returned to forward position in the bolt by ejector spring. 1| after ejection of the cartridge case, the operating spring 55 in conjunction with wall of recess 52 in the operating slide 50, pressing against the part 43a will return insert 43 to forward position -at beginning of counter-recoil travel of operating rod.

The extractor 60 is mounted 0n the upper left side of the bolt opposite the ejector in a channel 4E provided along the side of the bolt 40. It comprises a relatively long member having at its forward end a claw-shaped portion 6| adapted to engage the rim la of the cartridge l. The rear portion of the extractor 60 is provided with two oppositely disposed longitudinal ribs 62 (Fig. 8) which engage undercut slots (not shown) provided in the sides of the extractor channel 46 on the bolt 40. Near the forward end of the extractor 60 there is provided an integral extension 63 which projects within a recess 41 in the bolt 40. The front surface of extension 63 and the Wall of the recess 4l against which it abuts are sloped, so that the extractor must be bent slightly in order to permit extractor extension 63 to enter recess 41, whereafter the extractor 60 is held in place by the engagement between these two sloped surfaces. The springlike body of the extractor is suciently flexible to permit the claw 6| to be snapped outward to engage a cartridge rim la in theconventional fashion during loading of such cartridge. A portion of the claw 6|, indicated at 6m (Fig. 9), of the extractor 60 lies in front of extension 43a of the bolt insert 43 and serves to prevent that member from being moved forwardly out of the bolt 40.

The ease of assembly and disassembly of the bolt members constructed as described is readily apparent. All members, the insert 43, the ejector 10, ejector spring 1|, and the extractor 60 are held in their proper positions in the bolt by the extractor 63. Hence upon bending the extractor 6U to release extractor extension 63 from bolt recess 41, all the other parts are immediately released. Y

In operation, a loaded magazine is of course inserted into the receiver. By manually retracting the operating rod 50, the bolt locking lug 4m is cammed by the sides of the recess 52 in the operating rod to rotate and unlock the bolt, permitting the bolt to be retracted, to the position shown in Fig. 1. Upon release of the operating handle, both the handle and the connected bolt assemblage are moved forward under the force of the compressed operating spring 55.- During this forward movement a cartridge is picked up from the magazine I by the lower rim of the bolt face, as in Fig. 1, loaded into the chamber 3| of the barrel and the rim la of the cartridge engaged by the claw 6| of extractor 60 and the ejector forced rearwardly. The bolt is rotated into locked position by the camming action of the inclined walls of recess 52 and in this locked'positionthe bolt insert 43 abuts against the primer 5 and bushing 5 of the cartridge when utilizing a cartridge of the type disclosed in my co-pending application above referred to, while the solid bolt face abuts against the remainder of the rear face of the cartridge. The rearward movement of the bolt of course cocked the hammer 35 and putthe trigger mechanism in the ready-to-re position. Upon pulling the trigger 33, the sear 34`releases the hammer, the hammer strikes the rear end of the ring pin 42 which in turn strikes the primer 6 of the cartridge as shown 4in Fig. 2. As a result of the explosion the bushing 5 and the primer 6 of a cartridge of the type disclosed in my co-pending application above referred to ammunition is employed the primer only will be forced rearwardly. rhese elements however are in abutment with the insert member 43 and this member therefore receives a hammer-like rearward blow. This force imparted to the insert member i3 is in turn transmitted to the operating rod 50 through engagement of the insert extension 43a with the rear wall of the recess 52. Thus energy is transmitted to the operating rod which starts to move to the rear. It will be noted from Fig. 6 that appreciable rearward movement of the operating rod t must occur before the locking lug ila is cammed upward by the Walls of recess 52. The time required to complete this movement is appreciable due to relatively large inertia of the operating rod supplied by the mass of the inertia member 53 secured to the forward end of the operating rod. Thus suicient time is permitted to elapse before unlocking of the bolt to permit the pressure within the chamber to be reduced to a value permitting the safe opening of the bolt. It should be noted that the body of the cartridge is held tightly within the chamber until the bolt is unlocked, hence minimizing the possibility of rupture of the cartridge case. Upon unlocking the bolt the inertia of the operating rod 5B and inertia member 53 is sufficient to drive the bolt to the rear compressing operating spring The extractor claw El is, as Stated, hooked around the rim lo of the cartridge and withdraws the empty cartridge I from the chamber. As soon as the forward end of the cartridge case is freed from the chamber` the cartridge is ejected by the force of the compressed ejector spring 'Il acting on the rim of the cartridge through the ejector 19, The rearward movement of the bolt il of course cocks the hammer by overriding it in the conventional manner and thus returns the trigger assemblage to the firing position. The bolt strikes a suitable stop in the receiver and is returned to battery position by the compressed operating spring 55, loading a second cartridge as it returns. Whether the second cartridge is immediately fired, thus obtaining full automatic operation, or whether the trigger must be pulled again to fire the next cartridge oi course depends upon the particular trigger mechanism utilized and is independent of this invention.

It is therefore apparent that a firearm constructed in the manner described will provide consistent and reliable operation hitherto unobtainable in primer-operated guns. Furthermore, a minimum of parts and weight is obtained. It is further apparent that the described constructions are not limited to application in rines but may be applied to any form of automatic firearm, including machine guns.

I claim:

1. In a rearm, a receiver, a bolt reciprocably mounted therein, a lug on Said bolt engageable in locking relation with said receiver in the battery position of said bolt, means for moving said bolt to unlock said lug from said receiver, said bolt having a recess formed in the forward end thereof and extending into said lug, an insert mounted in said recess for limited movement along the bolt axis and having an arm disposed in the recessed portion of said lug, the front face of said insert being adapted to abut against the primer elements of a cartridge in the battery position of said bolt, said arm connecting with the aforementioned means for moving the bolt, whereby movement of said insert under force received from the primer elements of the cartridge actuates the aforementioned means to unlock the bolt.

2. The combination defined in claim 1 wherein said means for moving said bolt comprises an operating member reciprocatingly movable on said receiver, and a cam surface on said operating member engageable with said bolt lug to move said bolt out of locked relation with said receiver by rearward movement of said operating member.

3. In a firearm, a receiver, a bolt rotatable and reciprocatingly movable in said receiver, a plurality of radial locking lugs on said bolt movable on rotation of the bolt into locking relation with said receiver` in the battery position of said bolt, said bolt having a recess formed in the forward end thereof and extending into one of said lugs, an insert mounted in said recess for limited movement along the bolt axis and having an arm disposed in the recessed portion of said one lug, the front face of said insert being adapted to abut against the primer elements of a cartridge in the battery position of said bolt, an operating member reciprocably mounted on said receiver and constructed and arranged to rotatively unlock and to retract said bolt, said arm engaging said operating member to impart an actuating force thereto by rearward movement of said insert under force received from the primer elements of the cartridge.

4. In a rearm, a receiver, a bolt rotatable and reciprocatingly movable in said receiver, a plurality of radial locking lugs on said bolt movable on rotation of the bolt into locking relation with said receiver in the battery position of said bolt, said bolt having a recess formed in the forward end thereof and extending radially into and rearwardly through one of said lugs, an insert mounted in said recess for limited movement along the bolt axis and having an arm disposed in the recessed portion of said one lug, the front face of said insert being adapted to abut against the primer elements of a cartridge in the battery position of said bolt, an operating member reciprocably mounted on said receiver, a cam surface on said operating member engageable with said recessed bolt lug to thereby rotate and retract said bolt by rearward movement of said operating member, said arm projecting outwardly through said recessed bolt lug to engage said operating member, whereby rearward movement of said insert under force received from the primer elements of the cartridge actuates said operating member to unlock and retract said bolt.

EARLE M. HARVEY.

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