U.S. patent number 3,738,223 [Application Number 05/201,523] was granted by the patent office on 1973-06-12 for obturator-extractor device for firearms.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Army. Invention is credited to John S. Post, Frederick P. Reed.
United States Patent |
3,738,223 |
Post , et al. |
June 12, 1973 |
OBTURATOR-EXTRACTOR DEVICE FOR FIREARMS
Abstract
An obturator-extractor provides safe firing of cartridges having
cases made rom 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.
Inventors: |
Post; John S. (Davenport,
IA), Reed; Frederick P. (Davenport, IA) |
Assignee: |
The United States of America as
represented by the Secretary of the Army (Washington,
DC)
|
Family
ID: |
22746183 |
Appl.
No.: |
05/201,523 |
Filed: |
November 23, 1971 |
Current U.S.
Class: |
89/26; 42/16;
42/25 |
Current CPC
Class: |
F41A
3/74 (20130101); F41A 15/14 (20130101) |
Current International
Class: |
F41A
15/14 (20060101); F41A 3/74 (20060101); F41A
15/00 (20060101); F41A 3/00 (20060101); F41f
011/02 () |
Field of
Search: |
;89/26 ;42/16 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Tudor; H. J.
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 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
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.
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
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.
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.
Description
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.
It has 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 bolt-barrel 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 fired 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 10
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 20 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
obturator-extractor 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 cross-section, 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 70 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 bolt-chamber. 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 bolt-chamber.
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.degree. 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
cartridge-chamber 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.
* * * * *