US3738223A

US3738223A - Obturator-extractor device for firearms

Info

Publication number: US3738223A
Application number: US00201523A
Authority: US
Inventors: J Post; F Reed
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1971-11-23
Filing date: 1971-11-23
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12

Abstract

An obturator-extractor provides safe firing of cartridges having cases made from lightweight materials, such as aluminum, plastics, or other non-metallic materials, in a firearm with a reciprocating bolt comprising a conoidal bolt head that is receivable by a mating chamber in the barrel breech when the bolt is in locked battery position. A single piece obturator-extractor device is mounted as a shell on the bolt head and is comprised of convexly formed surfaces which make sealing contact with the barrel chamber and a tubular section which is receivable by a recess formed in the head to receive the rear end of the case. An extractor of cantilever configuration is provided on the tubular section of the obturator for engagement with the extractor groove in the case. In an alternate embodiment, the obturator device includes a dish-shaped washer and a truncated conoidal sleeve which are mounted in the front end and circumferential wall of the barrel chamber, respectively, to make resilient, obturating contact with the bolt head and the barrel chamber when the bolt is in locked battery position. The extractor is a separate split tubular member which is mounted in the head recess and which is provided with a chordal claw of torsion bar configuration.

Description

aten 1 1 Waited States Post et al.

[ .Hune 12, 1973 Primary ExaminerBenjamin A. Borchelt Assistant ExaminerH. J. Tudor Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl et al.

[57] ABSTRACT An obturator-extractor provides safe firing of cartridges having cases made from lightweight materials, such as aluminum, plastics, or other non-metallic materials, in a firearm with a reciprocating bolt comprising a conoidal bolt head that is receivable by a mating chamber in the barrel breech when the bolt is in locked battery position. A single piece obturator-extractor device is mounted as a shell on the bolt head and is comprised of convexly formed surfaces which make sealing contact with the barrel chamber and a tubular section which is receivable by a recess formed in the head to receive the rear end of the case. An extractor of cantilever configuration is provided on the tubular section of the obturator for engagement with the extractor groove in the case.

In an alternate embodiment, the obturator device includes a dish-shaped washer and a truncated conoidal sleeve which are mounted in the front end and circumferential wall of the barrel chamber, respectively, to make resilient, obturating contact with the bolt head and the barrel chamber when the bolt is in locked battery position. The extractor is a separate split tubular member which is mounted in the head recess and which is provided with a chordal claw of torsion bar configuration.

9 Claims, 7 Drawing Figures PMENFED 3.738.223

MM 3 BF 2' INVENTOR. John E 1 05 FnEdenicKF. REBEL OBTURATOR-EXTRACTOR DEVICE FOR FIREARMS BACKGROUND OF THE INVENTION This invention relates to guns for firing cartridge type ammunition and pertains more particularly to devices for obturating the cartridge chamber in the barrel and for extracting the cases therefrom.

Cartridge cases have traditionally been fabricated from brass. This has been an excellent metal for the purpose; it does, however, have the disadvantages of being a relatively heavy metal and one which is in critical supply in time of war. Consequently, the investigation of the use of lightweight materials, such as aluminum, plastics, etc., for cartridge cases suggests itself not only because of the light weight, but also the ready supply of such materials.

In the exploratory use of aluminum alloys for cartridge cases, problems have been encountered. One of these has to do with damaged or scratched cases rupturing during firing, causing the case to burn around the crevice whereby the escaping hypervelocity hot gases and heat are emitted from the breech end of the barrel resulting in catastrophic effects to both the weapon and the user. Itihas also been found that the intensities of the escaping gases and heat are intensified by the case material feeding the gases and thus increase the size of the exit path from the firearm. This, of course, is extremely dangerous to the operator. It is also severely destructive to the structure of the firearm because of the erosion caused thereby and because of the buildup of the molten case material on the boltbarrel structure as the hot vapors cool. Then, too, the extractor groove in the cartridge case provides a path and a trap for the hot gases and vapors and whereas standard type extractors carried by the bolt employ moving parts they are subject to failure through the effects of the heat and the sediment deposits.

Tests have proven, however, that even if a case should rupture during firing the chances of personal injury to the operator and damage to the firearm structure are eliminated when the barrel chamber is obturated sufficiently to control gas flow from the barrel breech.

SUMMARY OF THE INVENTION It is a principal object of this invention to provide for firearms, which fire cartridge type ammunition and which comprise a reciprocating bolt for delivering the cartridges to the barrel chamber and extracting the tired cases therefrom improved means for obturating the breech end of the barrel so as to prevent the flow of gases therefrom in event of a ruptured case.

It is a further object of this invention to provide for the reciprocating bolt a seal for the interspace between the bolt head and the receiving chamber for the bolt head in the locked battery position.

It is another object of this invention to provide in the bolt head a recess for isolating the extractor groove from the exit path of any hot gases or vapors in event the case should rupture.

It is a still further obhect of this invention to provide a single piece extractor that does not require any separate cooperating components.

It is still another object of this invention to integrally form the extractor as a cantilever structure in the obturator device.

It is still another and further object of this invention to integrally form the extractor claw as a torsion bar in a tubular body which is receivable by the recess in the bolt head.

A further object of this invention is to fill the annular recess for the extractor with the extractor tubular body thereby to restrict the circular gas flow that evolves.

These objects are achieved through this invention by forming on the front end of a longitudinally reciprocating bolt a conoidal head which is receivable by a mating chamber in the barrel breech and forming a recess in the head deep enough to receive the base of a cartridge including the extractor groove. A single piece obturator-extractor device is mounted as a shell on the bolt head and is comprised of convexly formed formed front and circumferential sections which are resiliently compressed by cooperating structure in the barrel chamber when the bolt is in locked battery position thereby sealing gas tight the interspace between the head and receiving chamber. The device also includes a tubular section receivable by the recess in the head from which tubular section an extractor claw of cantilever configuration is providd so as to be engageable with the extractor groove.

In an alternate embodiment, the obturator-extractor device is composed of separate components comprising an obturator device including a washer of dished configuration which is held in the barrel chamber by a sleeve of conoidal configuration, but which is concavely formed in longitudinal section, to seal, respectively, the front and circumferential areas of the interspace between the head and chamber. The extractor is a separate tubular member which is mounted within the recess in the head and in which an extracting claw of torsion bar configuration is provided.

The specific nature of the invention as well as other aspects and advantages thereof, will appear from the following description of two preferred embodiments which are illustracted in the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinally cross-sectioned view of a firearm volt-barrel structure showing the bolt out of battery position;

FIG. 2 is a view similar to FIG. 1 but showing the bolt in locked battery position;

FIG. 3 is an enlarged perspective view of the obturator-extractor device partially broken away to show the fastening tabs;

FIG. 4 is a view similar to FIG. 1 of an alternate embodiment, but showing the sleeve member in full;

FIG. 5 is a view similar to FIG. 4 but showing the sleeve cross-sectioned and the bolt in locked battery position;

FIG. 6 is an enlarged perspective view of the extractor shown in FIGS. 4 and 5; and

FIG. 7 is a view taken along line 7-7 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Shown in FIGS. 1-3 are portions of a firearm comprising a receiver 10, a barrel 12 mounted to the front end of the receiver and adapted for receiving a cartridge 14 for discharge, and a bolt 16 reciprocally disposed in the receiver for delivering the cartridge into the barrel responsive to movement to a battery position. Bolt 16, conventionally, serves to block the breech end of barrel 12 during discharge of cartridge 14 by a firing pin 17 and to extract the fired case 18 thereof from the barrel responsive to movement out of battery position.

Bolt 16 comprises a head 20 of conoidal configuration with a cylindrical recess 22 extending axially thereinto from front surface 23 and which is of annular configuration, for receiving base 26 of case 18. Recess 22 extends deep enough into head 20 to also receive extractor groove 28 of case 18 when base 26 thereof is seated in the recess. A pair of locking lugs 27 extend oppositely from bolt 16 for engagement with locking recesses 29 in receiver to lock the bolt in battery position.

Barrel 12 comprises a bolt-chamber 30 which extends axially thereinto from the breech end thereof to an annular shoulder 31 for receiving head when bolt 16 is in battery position and which includes a circumferential surface 32 that tapers inwardly and forwardly to conform to the configuration of the facing walls 34 of such head. A cartridge chamber 36 extends coaxially from shoulder 31 for receiving cartridge 14 responsive to battery position displacement of bolt 16.

An obturator-extractor device 38 is mounted as a shell on head 20 and has essentially the same configuration thereof except that tapered section 40 is convexly formed, as shown in FIG. 1, so as to bulge outwardly from the head, and front section 42, of ring configuration similar to front surface 23, is convexly formed so as to bulge outwardly therefrom. A tubular section 44 extends integrally from the inner edge of front section 42 into recess 22. An extractor 46 is integrally formed from tubular section 44 so as to extend inwardly and rearwardly therefrom, as a cantilever, for engagement either with extractor groove 28 when case 18 is seated in recess 22 or with the outer surface of cases not provided with an extractor groove. Obturator-extractor device 38 is secured to head 20 against rotational and axial displacement relative thereto by at least one tab 48 that extends from the rear end of the obturatorextractor device so as to be bent into a mating groove 50 which is formed at the rear of such head but in front of lugs 27.

Thus, when bolt 16 is displaced forwardly and angularly into locked battery position, through the engagement of locking lugs 27 with recesses 29, tapered section 40 is pressed against surface 32 of bolt chamber 30, so as to be resiliently compressed thereby; and front section 42 is pressed against shoulder 31, so as to be resiliently deformed thereby, to obturate the interspace between head 20 and bolt chamber 30. Consequently, if case 18 should be ruptured by discharge pressure the escaping gases are prevented from exiting rearwardly from barrel 12 and extractor groove 18 and extractor 46 are located away from any passage of hot gases.

Shown in FIGS. 4-7 is an alternate embodiment in which barrel 52 and bolt 54 are similar to their counterparts shown in FIGS. 1-3 except that an annular flange 56 extends around the rear end of bolt-chamber 58 to form thereat an annular shoulder 60 which is coincident with a plane normal to the longitudinal axis of the barrel. At the front of the bolt-chamber 58, an annular shoulder 59 is formed around the cartridge chamber 61. An annular shoulder 62 is formed also around the entrance to recess 64 in head 66 of the bolt. Obturation of the interspace between head 66 and bolt-chamber 58, when bolt 54 is in locked battery position, is effected by a washer 68 and a conoidal sleeve 70. Extraction of case 18 is effected by a tubular extractor 72 which is located in channel 62 as hereinafter described.

Washer 68 is of a dished configuration in crosssection, similar to a Belleville spring of the kind described in U. S. Pat. No. 75970, with the inside and outside dimensions thereof similar to those of front shoulder 59 with which it has contact. Washer 68 is held against front shoulder 59 by sleeve which is secured in bolt-chamber 58 between shoulder 60 and the washer. Sleeve 70 is tapered so that the outside diameter of front edge 74 thereof is essentially the same as that of the outside diameter of washer 68 and the outside diameter of rear edge 76 is essentially the same as the inside diameter of bolt-chamber 58 at shoulder 60. The wall of sleeve 70 is concavely formed in longitudinal cross-section so as to bulge inwardly and because the outside diameter of rear edge 76 is greater than the inside diameter of flange 56 the rear edge is interrupted by a plurality of slits 78 which permit sufficient compression of the uninterrupted sections 79 formed thereby for passage of the rear edge past the flange. When sleeve 70 is located in bolt-chamber 58 so that front edge 74 presses washer 68 against front shoulder 59, the uninterrupted sections 79 of rear edge 76 spring back to their normal positions for contact with shoulder 60 to secure sleeve 70 and the washer in such boltchamber. When bolt 54 goes into battery position, head 66 expands sleeve 70 to make resilient contact therewith and thereby front edge 74 is pressed against washer 68 and bolt-chamber 58 at the junction thereof and rear edge 76 is pressed against shoulder 60 to form three sealing points between the head and boltchamber.

Extractor 72 comprises a tubular body 80 which is receivable by channel 62 with a minimum of tolerance, and to permit insertion thereinto such body it is split to form facing ends 82 each of which is provided with a semi-circular recess 84 that is complementary to the other. Ends 82 are spaced so as to permit sufficient compression of body 80 for insertion into channel 62. Extractor 72 is secured against rotation at a predetermined relationship respective to ejector 86 by a pin 88 which is pressed into a mating hole 90 in head 66 and which is provided with a head 92 which is received by recesses 84 in body 80. Proper orientation is required not only to control the direction of ejection of case 18 by ejector 86, but also to provide for relief of excessive gas pressures in the chamber by means of the pin 88, in a manner more particularly described in applicants copending patent application. A relief cut 91 which extends 90 around body 80 and forwardly thereinto from the rear and thereof forms a web 92 which is rectangular in cross-section. Web 92 is straightened to a chordal configuration and twisted about its long axis so that an inner surface 94 inclines inwardly and rearwardly and rearwardly to a contact edge 96 thereby forming a claw or tang 98 which is receivable by extractor groove 28.

Thus, when bolt 54 goes into locked battery position, and the forward travel of cartridge 14 is stopped by contact with the front portion of cartridge-chamber 36, the continued forward travel of the bolt relative to the cartridge moves inner surface 94 of claw 98 against base 26 of case 18. The camming contact of base 26 with inner surface 94 twists claw 98, and the remaining portions of web 92, as a torque bar utilizing the contact of front edge 96 of the claw with shoulder 102 as a fulcrum. When contact edge 96 is in registry with extractor groove 18 it snaps thereinto ready to transfer the rearward movement of bolt 54 to fired case 18 for extraction thereof.

Extractor 72 is also especially well adapted for removing a caseless or rimless cartridge, that is, a cartridge not having an extractor groove, from barrel 52 should one of the cartridges prove to be a dud, which is one of the perplexing problems respective to the use of caseless or rimless ammunition.

For use with a caseless cartridge, contact edge 100 of claw 98 is provided with a sufficient sharpness so that the torque produced in claw 98 when the cartridge is engaged it thereby cuts thereinto during the rotation of bolt 54 to and from the locked battery position. The cartridge is held against rotation with the bolt through the frictional contact of the cartridge with cartridgechamber 36. Thus, claw 98 forms its own extractor groove in the cartridge and with contact edge 100 being located inwardly of front edge 96, which is the fulcrum for the rotation of the claw, the contact edge is forced further into the cartridge when bolt 54 begins its rearward travel from battery position.

it will become obvious to persons skilled in the art that forms other than the embodiment shown and described herein are possible within the spirit and scope of the present invention. Therefore, it is desired that the present invention shall not be limited except insofar as it is made necessary by the prior art and by the spirit of the appended claims.

We claim:

1. In a firearm for firing an ammunition round comprising a case having a base provided with an annular extractor groove, said firearm having a barrel with a chamber for receiving said round, the improvement wherein said firearm includes a longitudinally reciprocating bolt operatively disposed for feeding said round into said chamber for discharge responsive to movement of said bolt to a locked battery position, said bolt including a forwardly disposed head portion of conical configuration terminated by an annular front surface, said front surface having a centrally disposed recess extending rearwardly into said head portion for receiving at least a portion of said case base, said barrel chamber having a portion thereof of a configuration similar to that of said head portion for receiving said head portion responsive to movement of said bolt to a locked battery position, means on said bolt head portion for obturating the interspace between adjacent surfaces of said bolt head portion and said chamber portion incident to said bolt being disposed in a locked battery position, and extractor means disposed within said bolt head recess for engaging said cartridge case base.

2. The invention defined in claim 1 wherein said obturating means and said extractor means comprises a one-piece annular member, and includes fastening means for securing said annular member on said bolt 6 head portion.

3. The invention as defined in claim 2 wherein said one-piece annular member comprises a front section conforming to said front surface of said head and convexly formed in cross-section so as to normally bow outwardly therefrom, a tapered section surrounding the outside circumference of said bolt head portion and convexly formed so as to normally bow outwardly therefrom, and a tubular section disposed for extension into said bolt head portion recess from said front section.

4. The invention as defined in claim 3 wherein said extractor means is an integral part of said tubular section and is disposed for angular extension inwardly from said tubular section to function as a cantilever.

5. The invention as defined in claim 1 wherein said barrel chamber defines an annular front end shoulder and a rear flange having an annular front face, and wherein said obturating means comprises a Bellevilletype type washer disposed in said barrel chamber portion in contact with said front shoulder and a sleeve conforming substantially to the configuration of the walls of said barrel chamber portion between said front shoulder and said rear flange and formed convexly in longitudinal cross-section to bow outwardly respective to the walls of said chamber.

6. The invention as defined in claim 5 wherein said sleeve comprises a front edge having contact with said washer, a rear edge having contact with said front face of said flange and being responsive to movement of said bolt to the locked battery position to press said front edge against said washer and said rear edge against said front face thereby to effect sealing contacts at such contacted areas.

7. The invention as defined in claim 6 wherein said bolt head portion recess is expanded radially inwardly from said annular front surface to provide a front shoulder and said extractor means comprises a tubular body portion receivable by said expanded portion of said recess, and an integral claw provided on said tubu lar body portion disposed to function as a torsion bar.

8. The invention as defined in claim 7 wherein said extractor claw is of rectangular configuration in crosssection and comprises an inner surface which inclines inwardly and rearwardly terminating in a contact edge engageable with said cartridge responsive to movement of said bolt to the locked battery position, and a front edge having contact with said bolt head portion recess front shoulder to provide a fucrum for the angular displacement of said claw by said case and for forcing said contact edge inwardly responsive to rearward pressure applied thereagainst.

9. The invention as defined in claim 8 wherein said contact edge is sharply formed thereby to be capable of cutting a groove into said case responsive to rotation of said bolt to and from the locked battery position.

i l l

Claims

2. The invention defined in claim 1 wherein said obturating means and said extractor means comprises a one-piece annular member, and includes fastening means for securing said annular member on said bolt head portion.

5. The invention as defined in claim 1 wherein said barrel chamber defines an annular front end shoulder and a rear flange having an annular front face, and wherein said obturating means comprises a Belleville-type type washer disposed in said barrel chamber portion in contact with said front shoulder and a sleeve conforming substantially to the configuration of the walls of said barrel chamber portion between said front shoulder and said rear flange and formed convexly in longitudinal cross-section to bow outwardly respective to the walls of said chamber.

7. The invention as defined In claim 6 wherein said bolt head portion recess is expanded radially inwardly from said annular front surface to provide a front shoulder and said extractor means comprises a tubular body portion receivable by said expanded portion of said recess, and an integral claw provided on said tubular body portion disposed to function as a torsion bar.

8. The invention as defined in claim 7 wherein said extractor claw is of rectangular configuration in cross-section and comprises an inner surface which inclines inwardly and rearwardly terminating in a contact edge engageable with said cartridge responsive to movement of said bolt to the locked battery position, and a front edge having contact with said bolt head portion recess front shoulder to provide a fu crum for the angular displacement of said claw by said case and for forcing said contact edge inwardly responsive to rearward pressure applied thereagainst.