U.S. patent application number 15/587660 was filed with the patent office on 2017-11-16 for lightweight cartridge case and weapon system.
This patent application is currently assigned to U.S. Government as Represented by the Secretary of the Army. The applicant listed for this patent is U.S. Government as Represented by the Secretary of the Army. Invention is credited to Frank Dindl.
Application Number | 20170328690 15/587660 |
Document ID | / |
Family ID | 60266910 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170328690 |
Kind Code |
A1 |
Dindl; Frank |
November 16, 2017 |
Lightweight Cartridge Case and Weapon System
Abstract
The rifle system comprises a rifle and an ammunition round for
operation with the rifle. The high pressure ammunition round
further comprises a cartridge case having an outer wall wherein
prior to firing of the ammunition round, the outer wall geometry of
the cartridge case is devoid of features configured for interfacing
with a mechanical extractor. The rifle further comprising a barrel
chamber which fully supports a chambered cartridge case and a rear
extraction mechanism for extracting a spent cartridge case through
the rear of the barrel chamber.
Inventors: |
Dindl; Frank; (Newton,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
U.S. Government as Represented by the Secretary of the
Army |
Dover |
NJ |
US |
|
|
Assignee: |
U.S. Government as Represented by
the Secretary of the Army
Dover
NJ
|
Family ID: |
60266910 |
Appl. No.: |
15/587660 |
Filed: |
May 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62334620 |
May 11, 2016 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F42C 19/083 20130101;
F42B 5/26 20130101; F41A 21/28 20130101; F41A 15/04 20130101; F41B
11/62 20130101; F41A 15/12 20130101; F42B 39/087 20130101; F42B
5/30 20130101; F42B 5/02 20130101; F41A 15/00 20130101; F42B 5/28
20130101 |
International
Class: |
F42B 5/28 20060101
F42B005/28; F41A 15/12 20060101 F41A015/12; F41B 11/62 20130101
F41B011/62 |
Goverment Interests
STATEMENT OF GOVERNMENT INTEREST
[0002] The inventions described herein may be manufactured, used
and licensed by or for the United States Government.
Claims
1. A rifle for firing high pressure ammunition, the rifle
comprising: a barrel chamber which fully supports a chambered
cartridge case; and a rear extraction mechanism for extracting a
spent cartridge case through the rear of the barrel chamber.
2. The rifle of claim 1 wherein the operating pressure is in the
range of approximately 30,000 pounds per square inch to
approximately 200,000 pounds per square inch.
3. The rifle of claim 1 wherein when the rifle is in a chambered
state, an interior surface of the barrel chamber extends the length
of the chambered cartridge case such that the entire chambered
cartridge case is supported by the chamber.
4. The rifle of claim 1 wherein the rear extraction mechanism
comprises a gas extraction mechanism.
5. The rifle of claim 4 wherein the gas extraction mechanism is
operated by a residual bore pressure remaining in the chamber after
unlocking of a bolt of the rifle.
6. The rifle of claim 4 wherein the gas extraction mechanism
further comprises a reservoir for storing a stored propellant gases
created during the firing of the ammunition and an inlet passage
for reintroducing the stored propellant gases into the chamber.
7. The rifle of claim 4 wherein the gas extraction mechanism
further comprises an external tank holding pressurized gas for
introduction into the chamber of the rifle after firing of the
cartridge case.
8. The rifle of claim 1 wherein the rear extraction mechanism
comprises a bolt having a recessed bolt face further comprising a
tapered undercut wall configured for interfacing with an expanding
cartridge case.
9. A high pressure lightweight ammunition round configured for
being fully supported by a barrel chamber and comprising a
cartridge case having an outer surface wherein prior to firing of
the ammunition round, the outer surface is substantially devoid of
features configured for interfacing with a mechanical
extractor.
10. The high pressure ammunition round of claim 9 wherein the body
region of the cartridge case extends to a base of the case.
11. The high pressure ammunition round of claim 9 wherein the
cartridge case is formed of a metal material.
12. The high pressure ammunition round of claim 11 wherein the
cartridge case is formed of an aluminum material.
13. The high pressure ammunition round of claim 9 wherein the
cartridge case is formed of a polymer material.
14. The high pressure ammunition round of claim 9 wherein upon
firing of the ammunition round, the cartridge case of the
ammunition round expands into a tapered undercut wall of a recessed
bolt face of a bolt thereby facilitating extraction of the round by
the bolt.
15. The high pressure ammunition round of claim 9 wherein the
cartridge case further comprises an annular groove for interfacing
with a rear tab of a push through link wherein the annular groove
is defined by an outer surface of the cartridge case and extending
along an outer diameter of the outer surface.
16. The high pressure ammunition round of claim 15 wherein the
annular groove is sized and dimensioned to interface with an M27
push through link.
17. The high pressure ammunition round of claim 15 wherein the
annular groove is sized and dimensioned to interface with an M13
push through link.
18. The high pressure ammunition round of claim 15 wherein the
annular groove is sized and dimensioned to interface with an M15
push through link.
19. The high pressure ammunition round of claim 15 wherein the
annular groove is fire formed to a barrel chamber upon firing of
the high pressure of the ammunition round.
20. A rifle system comprising: a high pressure ammunition round
further comprising a cartridge case having an outer surface wherein
prior to firing of the ammunition round, the outer surface is
substantially devoid of features configured for interfacing with a
mechanical extractor; and a rifle further comprising a barrel
chamber which fully supports a chambered cartridge case and a rear
extraction mechanism for extracting a spent cartridge case through
the rear of the barrel chamber.
21. The rifle system of claim 20 wherein when the rifle is in a
chambered state, an interior surface of the barrel chamber extends
the length of the chambered cartridge case such that the entire
chambered cartridge case is supported by the chamber.
22. The rifle system of claim 20 wherein the rear extraction
mechanism of the rifle comprises a gas extraction mechanism.
23. The rifle system of claim 22 wherein the gas extraction
mechanism of the rifle is powered by a residual bore pressure
remaining in the chamber after unlocking of a bolt.
24. The rifle system of claim 22 wherein the gas extraction
mechanism of the rifle further comprises a reservoir for storing a
stored propellant gases created during the firing of the ammunition
and an inlet passage for reintroducing the stored propellant gases
into the chamber.
25. The rifle system of claim 22 wherein the gas extraction
mechanism of the rifle further comprises an external tank holding
pressurized gas for introduction into the chamber of the rifle
after firing of the cartridge case.
26. The rifle system of claim 20 wherein the rear extraction
mechanism of the rifle comprises a bolt having a recessed bolt face
further comprising a tapered undercut wall configured for receiving
an expanding cartridge case.
27. The rifle system of claim 26 wherein the cartridge case of the
ammunition round is configured for expanding into the tapered
undercut wall upon firing of the ammunition round thereby forming
the rear extraction mechanism.
28. The rifle system of claim 20 wherein a body region of the
cartridge case extends to a base of the cartridge case.
29. The rifle system of claim 20 wherein the cartridge case is
formed of a metal material.
30. The rifle system of claim 20 wherein the cartridge case is
formed of a polymer material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 USC
.sctn.119(e) of U.S. provisional patent application 62/334,620
filed on May 11, 2016.
BACKGROUND OF THE INVENTION
[0003] The invention relates in general to small arms weapons and
in particular to cartridge cases for small arms.
[0004] Centerfire ammunition cartridges have changed little since
the 8 mm Lebel cartridge, developed in 1886, ushered in the modern
era of high pressure centerfire cartridges. The evolution to the 8
mm Lebel ammunition cartridge began with the original design of a
self-contained cartridge developed by Samuel Pauly and Francois
Prelat in 1808 and includes the development of pin fired cartridges
by Casmir Lefaucheux in 1836 and the breech loading Sharps rifle of
the Civil War which initially fired paper cartridges but later
adopted to fire self-contained metallic cartridges. Widespread
adoption of self-contained metallic cartridge followed the
development of the Smith & Wesson Model 1 revolver in 1857. In
1867, the Eley-Boxer metallic centerfire cartridge case adopted by
the British military. The 8 mm Lebel was the first cartridge using
smokeless propellant to be made and adopted by any country.
[0005] Centerfire cartridges have changed little since these early
developments. High power centerfire cartridges have used relatively
thick, heavy cartridge case heads to support the firing loads. Most
cartridge cases are made of heavy brass for this reason. Case head
designs relying on mechanical extraction of the cartridge case
require that the rearmost portion of the cartridge case extend
beyond the rear of the chamber where they are largely unsupported.
This, typically, limits peak chamber pressures to below 60,000
pounds per square inch (psi). High power centerfire cartridge cases
constitute the majority of the weight of the complete
cartridge.
[0006] Conventional ammunition includes a cartridge case 101, a
projectile 103, a propellant 105 and a primer 107. Prior art FIG. 1
shows a conventional 5.56 NATO ammunition round known in the prior
art. The 5.56 NATO ammunition round is the standard cartridge for
NATO military forces as well other non-NATO military forces and is
exemplary of the features and drawbacks of conventional
ammunition.
[0007] The cartridge case 101 of the 5.56 NATO ammunition round is
made of brass and the entire ammunition round weighs approximately
190 grains or 12.3 grams without any links for belt feeding. The
cartridge case 101 accounts for a majority of this weight. The
cartridge case 101 is a tapered bottleneck case type having a neck
region 109, a shoulder region 111, a body region 113 and a head
region 115. The head region includes an extractor groove 117 and
rim 119 for interfacing with a conventional extraction
mechanism.
[0008] As illustrated by the 5.56 NATO ammunition round, the
thickness of the head region 115 is substantially thicker than the
thickness of the other regions of the cartridge case 101 due to
both the need for the extraction features 117 in the case 101 and
because the head region 115 of the case 101 is unsupported in the
barrel. As the head 115 of the case 101 is unsupported, the
material properties of the cartridge case 101 must be sufficient to
withstand the firing load. The thicker head 115 adds additional
size and weight to the cartridge case 101.
[0009] The primer 107 is inserted into a cavity formed in the head
115 of the cartridge case 101. The primer 107 also adds weight to
the ammunition 10 and takes up volume within the cartridge case
101. Additionally, the seam between the primer 107 and the
cartridge case 101 may leak thereby causing performance issues with
the ammunition round 2.
[0010] A need exists for an improved ammunition cartridge which is
lighter, less expensive, safer and can operate at higher chamber
pressures than conventional ammunition.
SUMMARY OF INVENTION
[0011] One aspect of the invention is a rifle system. The rifle
system comprises a rifle and an ammunition round for operation with
the rifle. The high pressure ammunition round further comprises a
cartridge case having an outer wall wherein prior to firing of the
ammunition round, the outer wall geometry of the cartridge case is
devoid of features configured for interfacing with a mechanical
extractor. The rifle further comprising a barrel chamber which
fully supports a chambered cartridge case and a rear extraction
mechanism for extracting a spent cartridge case through the rear of
the barrel chamber.
[0012] A second aspect of the invention is a rifle for firing high
pressure ammunition. The rifle includes a barrel chamber which
fully supports a chambered cartridge case and a rear extraction
mechanism for extracting a spent cartridge case through the rear of
the barrel chamber.
[0013] A third aspect of the invention is an ammunition round. The
high pressure ammunition round further comprises a cartridge case
having an outer wall wherein prior to firing of the ammunition
round, the outer wall geometry of the cartridge case is devoid of
features configured for interfacing with a mechanical
extractor.
[0014] The invention will be better understood, and further
objects, features and advantages of the invention will become more
apparent from the following description, taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In the drawings, which are not necessarily to scale, like or
corresponding parts are denoted by like or corresponding reference
numerals.
[0016] Prior Art FIG. 1 is a cross sectional view of a standard
NATO 5.56 mm ammunition round, in accordance with one illustrative
embodiment.
[0017] FIG. 2 is a sectional plan view of the rifle system in a
chambered position, in accordance with one illustrative
embodiment.
[0018] FIG. 3 is a sectional plan view of the rifle system in a
firing position, in accordance with one illustrative
embodiment.
[0019] FIG. 4 is a sectional plan view of the rifle system in an
extraction position, in accordance with one illustrative
embodiment.
[0020] FIG. 5 is a sectional plan view of a rifle comprising a gas
extraction mechanism, in accordance with one illustrative
embodiment.
[0021] FIG. 6 is a cutaway perspective view of the barrel chamber
of the rifle comprising a recessed bolt extraction mechanism and a
cartridge case in an uncaptured state, in accordance with one
illustrative embodiment.
[0022] FIG. 7 is a cutaway perspective view of a barrel chamber of
the rifle comprising a recessed bolt extraction mechanism and a
cartridge case in a captured state, in accordance with one
illustrative embodiment.
[0023] FIG. 8 is sectional plan view of a cartridge case with a
consolidated propellant charge serving as the primer cup and anvil,
in accordance with one illustrative embodiment.
[0024] FIG. 9 is a sectional plan view of a cartridge case with an
integral primer cup, in accordance with one illustrative
embodiment.
[0025] FIG. 10 is a sectional plan view of a percussion primed
cartridge case with an integral primer cup, in accordance with one
illustrative embodiment.
[0026] FIG. 11 is a sectional plan view of a cartridge case with a
conventional primer cup, in accordance with one illustrative
embodiment.
[0027] FIG. 12 includes FIG. 12a which is a sectional plan view of
a cartridge case with a conventional primer cup and non-tapered
walls and 12b which is a sectional perspective view of a cartridge
case with conventional primer cup and non-tapered walls, in
accordance with one illustrative embodiment.
[0028] FIG. 13 includes FIG. 13a which is a sectional plan view of
a cartridge case with a hybrid cartridge case and a metal base and
FIG. 13b which is a sectional perspective view of a cartridge case
with a hybrid cartridge case and a metal base, in accordance with
one illustrative embodiment.
[0029] FIG. 14 is a plan view of a lightweight cartridge case with
an annular groove, in accordance with one illustrative
embodiment.
[0030] FIG. 15 is a sectional plan view of a lightweight cartridge
case with an annular groove, in accordance with one illustrative
embodiment.
[0031] FIG. 16 is a sectional plan view of a fired lightweight
cartridge case with an annular groove where the annular groove has
been fire formed to the chamber dimensions, in accordance with one
illustrative embodiment.
[0032] FIG. 17 is a perspective view of a cartridge case with an
integral linked belt, in accordance with one embodiment.
[0033] FIG. 18 is a perspective view of a cartridge case with an
integral linked belt, in accordance with one embodiment.
[0034] FIG. 19 is a plan view of a cartridge case configured for
linking with a string, in accordance with one embodiment.
[0035] FIG. 20 is a plan view of a cartridge case configured for
linking with a string, in accordance with one embodiment.
[0036] FIG. 21 is a perspective view of multiple cartridge cases
linked with a string, in accordance with one embodiment.
DETAILED DESCRIPTION
[0037] A rifle system having a rifle and accompanying ammunition
allows for ammunition with a reduced weight cartridge case. The
reduced weight of the cartridge case may lower the load on the
soldier or may increase the performance of the rifle by allowing
for more propellant to be included in an ammunition round.
[0038] Rifle, as used throughout this specification refers to a
firearm which operates with peak chamber pressures in the range of
approximately 40,000 to 190,000 pounds per square inch. The rifle
may fire a single projectile or may fire projectiles in an
automatic or semi-automatic firing mode. Additionally, the rifle
may be either magazine fed or belt fed. As an example, conventional
rifles which may be modified for use in the rifle system include
the 5.7 mm P90, 5.56 mm M4, 5.56 mm M16/AR15, 7.62 mm M40 or M24
sniper rifles, .50 caliber M82A1/M107, 14.5 mm, 20 mm, 5.56 mm
M249, 7.62 mm M240, .50 caliber M2, 20 mm M61, 25 mm M242, 30 mm
GAU-8 and MK44, Bushmaster III 35/50 mm, 40 mm Bushmaster IV, 40 mm
Bofors L/70, and Bofors 57 mm and other rifle calibers. However,
the rifle isn't limited to modified versions of existing
rifles.
[0039] The rifle includes a rear extraction mechanism which doesn't
rely on an extractor groove as is typical of conventional
centerfire cartridges. By eliminating the conventional extractor
from the rifle, the barrel chamber may be modified to fully support
the base of an ammunition round chambered in the rifle.
[0040] The ammunition round is suited for peak chamber pressures in
the range of approximately 40,000 to 190,000 psi. More
specifically, the ammunition round is particularly suited for peak
chamber pressures in the range of approximately 50,000 to 150,000
psi. The lightweight ammunition round described herein may provide
the equivalent functionality of conventional ammunition in a range
of calibers. For example, the modified lightweight ammunition round
may be a modified equivalent of the ammunition associated with the
above listed firearms.
[0041] The ammunition round is devoid of the extractor groove found
in traditional ammunition. Additionally, as the cartridge case is
fully supported within the barrel, the cartridge case does not have
to support the full firing load experienced during firing of the
ammunition round.
[0042] Advantageously, the cartridge case is lighter than most
conventional cartridge cases. The cartridge case requires less
material to be used due to having thinner walls and the amount of
head material being reduced. Additionally, alternative materials
such as aluminum, steel or polymer materials may be used for the
cartridge case as the full firing load is no longer supported by
the cartridge case.
[0043] Weight reductions in the range of approximately 50% may be
achieved over equivalent conventional ammunition. For example, as
will be described in further detail below, in one embodiment in
which a polymer case is employed, a belt fed modified lightweight
5.56 mm M855A1 ammunition round weighs approximately 96.3 grains
whereas a belt fed conventional 5.56 mm M855A1 ammunition round
weighs approximately 222 grains.
[0044] As the full support of the case addresses chamber pressure
limitations associated with conventional ammunition, the
lightweight cartridge case may be configured to operate at higher
chamber pressures of the rifle to reduce the amount of propellant
required to achieve a given muzzle velocity. Alternatively, the
reduced weight and volume of the cartridge case may allow for the
use of more propellant in the same weight and size profile of
conventional ammunition thereby increasing performance.
[0045] In another embodiment, the lightweight ammunition rounds may
include lightweight projectiles with high density penetrators to
further reduce cartridge weight while providing increased lethality
and armor penetration at short ranges due to the increased muzzle
velocities associated with using lightweight projectiles.
[0046] A primer cup may be formed integrally to the cartridge case
further reducing the volume and weight of the cartridge case. By
having an integral primer cup and cartridge case, the ammunition
round is more safe and robust as the seam between the primer cup
and the cartridge case is eliminated. Additionally, eliminating
this seam eliminates the "burn-through" failure mode associated
with conventional high power cartridges with aluminum cases.
[0047] Additional safety features may be realized due to the case
being fully supported. The risk of cook off is significantly
reduced. During cook-off, the greatest hazard to the operator of
the weapon is when the cartridge is partially chambered but the
bolt is not locked. A conventional cartridge case ruptures at a
high pressure due to the strength required by conventional cases.
However, the relatively thin walls of the lightweight ammunition
cartridge rupture at much lower and less hazardous pressure.
Additionally, the hazard from fragments is lowered due to the
lightweight, thin walled cartridge case failing at lower pressures
and producing lower kinetic energy fragments compared to
conventional brass cased cartridges.
[0048] FIG. 2 is a sectional plan view of the rifle system in a
chambered configuration, in accordance with one illustrative
embodiment. The rifle system includes a rifle 30 and an ammunition
round 2. As shown, the rifle system is in a chambered configuration
with an ammunition round 2 chambered in the barrel 301 of the rifle
30. The ammunition round 2 may be fed into the chamber 301 from a
magazine using magazine feeding means known in the art.
Alternatively, as will be described in further detail below, the
ammunition round 2 may be belt-fed into the chamber.
[0049] The ammunition round 2 comprises a cartridge case 20, a
primer 26 and a propellant charge 24 housed within the cartridge
case 20 and a projectile 22 secured to a forward end of the
cartridge case 20. As will be described in further detail below, in
the embodiment shown, a primer composition 261 is secured inside
the base 205 of the cartridge case 20 by the cartridge case 20 and
the propellant charge 22 forming a primer cup 263. The propellant
charge 22 shown in FIG. 2 is a consolidated propellant charge 22
which serves as an anvil 265 to ignite the primer composition 26.
Alternatively, an anvil 265 may be inserted between the propellant
charge 22 and the primer composition 26.
[0050] In a chambered configuration, the cartridge case 20 is
seated in the chamber 301 of the barrel 301. An inner surface of
the barrel chamber 301 supports the entire length of the cartridge
case 20 in the chamber, particularly including the region preceding
the base of the cartridge case 20. A bolt 303 of the rifle 30 is
seated against an outer surface of the base 205 of the cartridge
case 20. A firing pin 305 of the rifle 30 is slidably disposed
within the bolt 303.
[0051] FIG. 3 is a sectional plan view of the rifle system in a
firing configuration, in accordance with one illustrative
embodiment. To fire the ammunition round 2, the firing pin 305
strikes the base 205 of the cartridge case 20 thereby indenting the
cartridge case 20. The primer composition 261 is pinched between
the indented cartridge case 20 and the anvil 265 of the propellant
which initiates the primer composition 261. Hot gases produced by
the primer composition 261 reaction ignites the propellant charge
22. Hot, high pressure gases pressure the chamber 301 and propel
the projectile 22 thru a bore of the barrel 301.
[0052] FIG. 4 is a sectional plan view of the rifle system in an
extraction position, in accordance with one illustrative
embodiment. Subsequent to firing the ammunition round 2, the bolt
303 moves rearward. As the bolt 303 translates rearward, the fired
cartridge case 20 is held against the bolt 303 by the residual
pressure in the bore of the barrel 301. As the cartridge case 20
travels rearward with the bolt 303, an ejector engages the fired
cartridge case 20 and redirects the cartridge case 20 out of an
ejection port of the rifle 30. Muzzle devices, such as conventional
muzzle suppressors may be used to boost the duration and pressure
of the residual bore pressure during case extraction.
[0053] FIG. 5 is a sectional plan view of a rifle comprising a gas
extraction mechanism, in accordance with one illustrative
embodiment. The duration and pressure of the residual bore pressure
may be adjusted by trapping propellant gases during firing. Trapped
propellant gases may then be reintroduced to the bore after firing
to assist in extraction of the case. Alternatively, compressed
gases from an external source may be introduced into the bore
subsequent to firing to assist in ejection of the cartridge case
20. The trapped gases may be stored in a gas housing 307 such as a
cylinder or reservoir which is mounted to the barrel 301 and
contains an inlet 309 to the bore of the barrel 301.
[0054] FIG. 6 is a cutaway perspective view of the barrel chamber
of the rifle comprising a recessed bolt extraction mechanism in an
uncaptured position, in accordance with one illustrative
embodiment. In an alternative embodiment, the rifle 30 comprises a
dynamically formed extractor. In this embodiment, the bolt 303
comprises a recess 603 defined by the face 601 of the bolt 303. The
recess 603 is sized and dimensioned to receive a rear portion of
the cartridge case 20 when pressed against the cartridge case 20.
The recess 603 further comprises an undercut 605, such as a tapered
undercut, defined by an inner circumferential surface of the recess
603.
[0055] FIG. 7 is a cutaway perspective view of the barrel chamber
of the rifle comprising a recessed bolt extraction mechanism and a
cartridge case in a captured position, in accordance with one
illustrative embodiment of the invention. In a chambered
configuration of the rifle 30 system, the rear portion of the
cartridge case 20 is received within the recess 603 with the recess
603 surrounding the rear portion. Upon firing of the ammunition
round 2, the thin walled cartridge case 20 expands into the
undercut 605 thereby dynamically forming an extraction feature in
the case. As the bolt 303 travels rearward, the cartridge case 20
is pulled along until interfacing with an ejector (not shown). The
dynamically formed extractor may be employed in lieu of gas
extraction of the cartridge case 20 or used in conjunction with gas
extraction of the cartridge case 20.
[0056] In an alternative embodiment, an interference extractor
provides the extraction force on the cartridge case 20. The
interference extractor engages with the cartridge case 20 via an
interference fit. The interference extractor pushes along the outer
circumferential surface of the cartridge case 20 during feeding and
chambering and provides adequate grip to extract the fired or
unfired case. Advantageously, with such an interference extraction
mechanism, both fired and unfired cartridge cases may be removed.
An interference extractor is particularly suited for use with
polymer cartridge cases.
[0057] FIG. 8 is sectional plan view of a cartridge case with a
consolidated propellant charge serving as the primer cup and anvil
265, in accordance with one illustrative embodiment. The exemplary
ammunition round 2 shown in FIG. 8 comprises a cartridge case 20,
primer composition 26, propellant charge 22 and a projectile 22.
The cartridge case 20 shown in FIG. 8 is a cylindrical
straight-walled cartridge case 20. The straight-walled cartridge
case 20 is particularly suited for use with consolidated propellant
charges as the straight walls do not impede the insertion of the
propellant charge into the cartridge case 20. However, in other
embodiments, such as those embodiments which do not employ a
consolidated primer charge, the walls are not straight and include
a neck region and a shoulder region.
[0058] The cartridge case 20 shown in FIG. 8 comprises a
cylindrical body region 203 extending from the case mouth 201 to
the base 205 of the cartridge case 20. A base 205 of the cartridge
case 20 is integral with the cylindrical body 203 of the cartridge
case 20 and is of substantially the same thickness as the body 203
of the cartridge case 20. The cartridge case 20 does not include a
head region or rim and is devoid of any extractor features, such as
the extractor groove, found on conventional ammunition.
[0059] The walls of the cartridge case 20 are of substantially the
same thickness along the entire axial length of the body 203. In
comparison to conventional ammunition, the walls of the cartridge
case 20 are relatively thin. In particular, the absence of the
thicker head region and base 205 reduces the volume of case
material required for the cartridge case 20.
[0060] Accordingly, as the head region and extraction features are
eliminated and the cartridge case 20 walls are thinner, the
cartridge case 20 is lighter. Additionally, the reduction in
material allows for the lightweight ammunition round 2 to achieve
the same performance as an equivalent conventional ammunition in a
smaller profile round. Alternatively, the lightweight ammunition
round 2 may have the same outer profile as an equivalent
conventional ammunition with more volume available in the interior
cavity. This additional volume may be utilized to increase
performance by including more propellant in the round.
[0061] To further reduce cartridge weight, the ammunition round 2
may be made of lighter and cheaper materials than conventional
ammunition. As the ammunition round 2 is fully supported within the
chamber, materials with the strength of brass are not required. For
example, the ammunition cartridge may be made of steel, aluminum or
a polymer material. The polymer material may be a sulfone polymer
material such as Radel.RTM. polyphenylsulfone (PPSU) material
available from Sulvay S.A. located in Neder-Over-Heembeek,
Brussels, Belgium. However, the ammunition cartridge is not limited
to being made of steel, aluminum or polymer. The cartridge case 20
may be made of any material suitable to withstand chamber pressures
in the ranges specified above.
[0062] The body 203 and base 205 together define an interior cavity
of the cartridge case 20 with an opening at the mouth 201 of the
cartridge case 20. A projectile 22 is inserted into the interior
cavity of the cartridge case 20. Primer composition 261 and a
propellant charge 22 fill the remaining volume of the cavity.
[0063] In the embodiment shown, the propellant charge 22 is a
consolidated propellant charge 22 which serves to secure the primer
composition 261 within the interior cavity as well as to serve as
the anvil 265 for initiating the primer composition 26. The
consolidated propellant charge 22 comprises a cavity for receiving
the primer composition 261 formed in a bottom surface of the
charge. The bottom surface of the consolidated propellant charge 22
is in communication with the primer composition 261 and is of
sufficient strength to serve as the anvil 265. In alternative
embodiments of the invention, an external anvil 265 may be inserted
into the inner cavity and between the propellant charge 22 and the
primer composition 261. Additionally, the propellant is not limited
to consolidated propellants. The propellant may be compacted in the
cartridge case 20, as well.
[0064] In addition to the weight reductions and performance
enhancements achieved through the cartridge case 20 dimensions and
material properties, as the cartridge case 20 is fully supported
within the chamber, the rifle 30 and ammunition round 2 may be
configured to operate at higher chamber pressures. Accordingly,
less propellant may be required in the lightweight ammunition round
2 to achieve the same results as conventional ammunition. This
serves to further reduce the volume and weight of the ammunition
round 2.
[0065] In operation, the firing pin 305 strikes the base 205 of the
cartridge case 20 which pinches the primer composition 261 between
the cartridge case 20 and the propellant charge 22 or anvil 265.
Advantageously, as the primer composition 261 is secured by the
propellant charge 22, a peripheral primer cup and the associated
added weight, cost and complexity are eliminated.
[0066] The weight of the lightweight ammunition round 2 is
approximately 50% lighter than an equivalent conventional
ammunition round. For example, the M855A1 ammunition round with an
M27 metallic belt has a total weight of approximately 222 grains.
The conventional brass case comprises 105 grains. The conventional
propellant weighs approximately 22 grains. The projectile weighs
approximately 62 grains. The conventional primer weighs
approximately 3.2 grains with the primer cup and anvil accounting
for approximately 3 grains. The link weighs 30 grains.
[0067] In comparison, an equivalent lightweight ammunition round 2
having a polymer cartridge case 20 and operating at a peak chamber
pressure of 100,000 pounds per square inch and having a muzzle
velocity equivalent to a convention M855A1 weighs approximately 97
grains. The polymer cartridge case 20 of the ammunition round 2
weighs approximately 15 grains. This is 90 grains, or approximately
86%, lighter than a conventional cartridge case. The propellant
charge weighs approximately 18 grains. Note that due to the higher
chamber pressures enabled by fully supporting the cartridge case
20, less propellant is required to achieve the same muzzle velocity
as the conventional M855A1. The projectile weighs approximately 62
grains. The primer weighs approximately 1 grains. The polymer link
weighs approximately 1 grain.
[0068] The ammunition round 2 described above is one embodiment of
the invention. Individual components may be modified according to
application to increase or decrease the performance. For example,
the above weights are for a percussion primed cartridge case 20.
Alternatively, laser ignition may be utilized to ignite the primer
composition thereby negating the need for an anvil and further
reducing the weight by at least 1 grain.
[0069] FIG. 9 is a sectional plan view of a cartridge case with an
integral primer cup, in accordance with one illustrative
embodiment. The cartridge case 20 shown in FIG. 9 is a bottleneck
cartridge having a neck region 207 and a shoulder region 209. The
lightweight cartridge case 20 is devoid of a head region, rim and
extraction features of conventional ammunition.
[0070] The cartridge case 20 further comprises a primer cup 263
integral to the cartridge case 20. The primer cup 263 is formed in
the interior surface of the base 205 of the cartridge case 20 and
holds the primer composition 26. An anvil 265 sits above the primer
composition 261 and between the primer composition 261 and the
propellant charge 22 and further secures the primer composition 261
in the primer cup 263. The anvil 265 is attached to the cartridge
case 20 by a thread, crimp, weld, adhesive, or other means and may
be made of brass, steel, aluminum, polymer or a combustible
material. The anvil 265 further comprises one or more flash tubes
267 for directing the hot gases of the primer composition 261 to
the propellant charge 22.
[0071] In operation, the base 205 of the cartridge case 20 is
indented by the firing pin 305. The primer composition 261 is
pinched between the base 205 of the cartridge case 20 and the anvil
265. Hot gases are produced by the primer composition 261 and
directed to the propellant charge 22 by the flash tubes 267. As the
propellant does not secure the primer composition 261 or serve as
the anvil 265, the propellant may be a non-consolidated
propellant.
[0072] Advantageously, the joint between the primer cup and the
cartridge that exists in conventional ammunition is eliminated.
This also reduces the weight associated with the conventional
metallic separately loaded primer. For aluminum cartridge cases,
the integral primer cup 263 eliminates the potential for "burn
through" by eliminating the potential leak path at the joint
between the case and the primer cup. For polymer cartridge cases,
the integral primer cup eliminates the need for a primer support
typically used in polymer cartridge cases, including conventional
polymer cartridge cases and polymer cased telescoped cartridge
cases.
[0073] FIG. 10 is a sectional plan view of a percussion primed
cartridge case 20 with an integral primer cup, in accordance with
one illustrative embodiment. The cartridge case 20 shown in FIG. 10
is a polymer cartridge case 20 having an integral primer cup 263.
The cartridge case 20 is a bottleneck cartridge having a neck
region 207 and a shoulder region 209. While the lightweight
cartridge case 20 is devoid of a rim and extraction features of
conventional ammunition, the cartridge case 20 comprises a head
region 211 surrounding the integral primer cup 263 and anvil 265. A
recess is formed in the base 205 of the cartridge case 20 for
serving as the primer cup 263 and receiving the anvil 265.
[0074] FIG. 11 is a sectional plan view of a lightweight cartridge
case with a conventional primer cup, in accordance with one
illustrative embodiment. The cartridge case 20 is not limited to
having an integral primer cup 263. The embodiment shown in FIG. 11
is configured for receiving a peripheral primer 26 such as a Berdan
primer 26.
[0075] The cartridge case 20 is a bottleneck cartridge case 20
having uniformly thin walls for the base 205 and body 203 of the
cartridge case 20. The cartridge case 20 further comprises a neck
region 207 and shoulder region 209 and is devoid of a head region
and extraction features. A recess for receiving the primer cup 263
is defined by the outer surface of the base 205 and extends into
the interior cavity of the cartridge case 20. Unlike conventional
cartridge cases, the primer cup recess 213 is not surrounded by a
head region of the cartridge case 20. An opening is formed in the
base 205 of the primer cup recess 213 thereby allowing the gases of
the primer to interact with the propellant charge 24 of the
interior cavity.
[0076] FIG. 12 includes FIG. 12a which is a sectional plan view of
a cartridge case 20 with a conventional primer and non-tapered
walls and 12b which is a sectional perspective view of a cartridge
case 20 with conventional primer and non-tapered walls, in
accordance with one illustrative embodiment. The cartridge case 20
shown in FIG. 12a and FIG. 12b is a straight wall cartridge case 20
having a base 205 configured for receiving a peripheral primer
26.
[0077] The cartridge case 20 comprises a body region 203 having
thin walls, a head region 211 and a base 205. There is an opening
in the head for receiving a base 205 and the interior surface of
the head region 211 has mating features for interfacing with and
connecting to a peripheral base 205 of the cartridge case 20. The
base 205 and head region 211 may be of the same material or may be
different materials.
[0078] The base 205 comprises reciprocal mating features for
interfacing and connecting to the head region 211 and is further
configured for receiving a peripheral primer 26, such as a Berdan
primer. The base 205 comprises a recess defined by the outer facing
surface of the base 205 for receiving the primer 26. An opening is
formed in the base of the primer cup recess 213 thereby allowing
the gases of the primer composition to interact with the propellant
charge 24 of the interior cavity.
[0079] FIG. 13 is a sectional plan view of a cartridge case with a
hybrid cartridge case and a metal base, in accordance with one
illustrative embodiment. In the embodiment shown in FIG. 13, the
cartridge case 20 is a straight-walled case having a polymer body
region 203 and head region 211 and a metal base 205. The body
region 203 comprises thin walls and defines the inner cavity of the
cartridge case 20.
[0080] The head region 211 extends from the cartridge case 20
forming the base of the interior cavity further defines the primer
cup 263. A primer cup recess 213 is formed in the head region 211
defined by the bottom surface of the head 211 and extended axially
into the head region 211. The head region 211 further comprises
integrally formed primer features including an anvil 265 and one or
more flash tubes 267. The head 211 is dimensioned for being
partially inserted into the metal base 205. The base 205 of the
cartridge case 20 is a hollow metal cylinder with an opening formed
in the proximate end of the cylinder.
[0081] FIG. 14 is a plan view of a lightweight cartridge case with
an annular groove, in accordance with one illustrative embodiment.
FIG. 15 is a sectional plan view of a lightweight cartridge case
with an annular groove, in accordance with one illustrative
embodiment. The ammunition round 2 may be magazine fed or belt fed
into the chamber 301 of the rifle 30. For the ammunition round 2 to
be belt fed by a conventional push through belt, such as an M27
ammunition belt, M13 ammunition belt or the M15 ammunition belt, an
annular groove 221 is formed in the outer circumferential surface
of the cartridge case 20. The annular groove 221 interfaces with a
rear tab of a push through belt.
[0082] The lightweight cartridge case 20 is a bottleneck cartridge
comprising a neck region 207, shoulder region 209, body region 203
and base 205. The cartridge case 20 has thin walls in each region.
A recess is formed in the base 205 to receive a peripheral primer.
However, in other embodiments, the primer may be integral to the
cartridge case 20.
[0083] The annular groove 221 is located near the base 205 of the
cartridge case 20 in place of the extractor groove found on a
conventional cartridge case. The annular groove 221 may be machined
into the cartridge case 20. Alternatively, the annular groove 221
may be grove rolled into the cartridge case 20. In the embodiment
shown in FIG. 15, the annular groove 221 does not increase the wall
thickness at the annular groove 221 thereby maintaining the weight,
volume and material savings achieved by the lightweight ammunition
round 2.
[0084] FIG. 16 is a sectional plan view of a fired lightweight
cartridge case with an annular groove where the annular groove has
been fire formed to the chamber 301 dimensions, in accordance with
one illustrative embodiment. In operation, a straight wall body 203
may be fire formed. Subsequent to the firing of the cartridge case
20, the hot gases within the cartridge case 20 20 may provide a
force against the interior cavity of the cartridge case 20 such
that the annular groove 221 is deformed and the cartridge case 20
conforms to the interior geometry of the barrel chamber 301.
[0085] FIG. 17 is a perspective view of a cartridge case with an
integral linked belt, in accordance with one embodiment. In an
embodiment of the invention, the cartridge case 20 is a polymer
case with an integral linked belt 291 for linking multiple
cartridge cases 20a . . . n. The integral linked belt 291 comprises
one or more protrusions 293 integral to the cartridge case 20 and
extending radially out from the outer circumferential surface of
the cartridge case 20. Each protrusion 293 links the cartridge case
20 to another cartridge case 20. By linking a plurality of
ammunition rounds 2 sequentially, an integral linked belt 291 for
feeding the ammunition into the chamber 301 of the rifle 30 is
formed.
[0086] In the embodiment shown in FIG. 17, each cartridge case 20
comprises four integral links 293 (i.e. protrusions 293). However,
the cartridge case 20 is not limited to four integral links 293.
There may be more than four links 293 or less than four links 293
dependent on the application. Two integral links 293 extend
radially out from a right side of the cartridge case 20 to link the
cartridge to a preceding cartridge case 20. Two integral links 293
extend radially out from the left side of the cartridge case 20 to
link the cartridge case 20 to a subsequent cartridge case 20.
Advantageously, the integral link belt 291 may be fed from a
forward end or a back end as it is reversible.
[0087] Each protrusion 293 extends from a recessed portion 295 of
the cartridge case 20 extending around the circumference of the
cartridge case 20 and having a width along the axial direction of
the cartridge case 20. The recessed portion 295 of the cartridge
case 20 has an outer diameter that is smaller than the outer
diameter of the non-recessed portions of the body 203 of the
cartridge case 20. The recessed portion 295 is located at a
mid-section of the body 203 of the cartridge where the cartridge
case 20 is well-supported by the chamber 301 during firing. By
locating it away from the base 205 or shoulder of the cartridge
case 20, case failure during firing may be avoided. Additionally,
the non-recessed portions of the cartridge case 20 in the axial and
distal ends of the cartridge case 20 seal the chamber 301 and
experience the most demanding conditions during firing.
[0088] The rifle 30 further comprises a detachment mechanism, such
as a blade. During the process of feeding the ammunition round 2
into the chamber 301 of the barrel 301, the detachment mechanism
cuts the relatively thin polymer protrusion 293 to separate the
round about to be chambered. While the round is being chambered,
the cut protrusion 293 is forced to wrap into the recessed portion
of the cartridge case 20.
[0089] The protrusion 293 may be molded or co-molded to the
cartridge cases 20. One preferred material for the cartridge case
20 and integral link is Radel.RTM. polyphenylsulfone (PPSU)
material available from Sulvay S.A. located in Neder-Over-Heembeek,
Brussels, Belgium. Radel.RTM. PPSU provides the necessary strength,
flexibility and impact resistance while still being easily cut.
[0090] FIG. 18 is a perspective view of a cartridge case 20 with an
integral linked belt, in accordance with one embodiment. In an
alternative embodiment of the case, the integral links 293 may
extend out from the outer surface at an angle as opposed to
radially. In the embodiment shown in FIG. 18, two integral links
293 extend from the right outer surface of the cartridge case 20 at
an angle of 45 degrees with respect to a central axis of the
cartridge case 20. Each of the two links is connected to an
integral link 293 from a preceding cartridge case 20 thereby
forming a "v" shape.
[0091] FIG. 19 is a plan view of a cartridge case 20 configured for
linking with a string, in accordance with one embodiment. In an
embodiment of the invention, the cartridge cases 20 are linked via
a string link 297. The string 297 can be attached either during
case molding or subsequent to case molding. The cartridge case 20
comprises one or more string link grooves 299 extending annularly
along the outer circumferential surface of the cartridge case 20.
The one or more grooves 299 are employed to secure the string link
297 in the proper location for the link configuration that is
attached after the case is molded.
[0092] A weak point can be engineered at the midpoint in the string
link 297 between cartridges. The weak point may be a knot in the
string or may be a laser cut.
[0093] Advantageously, the string link 297 is more flexible,
stronger and lighter than a link made from the cartridge case 20
material. Additionally, the string 297 is received into the annular
grooves 299 thereby providing a smoother outer profile to aid
chambering of the ammunition round 2.
[0094] In the embodiment shown in FIG. 19, the cartridge case 20
comprises two annular string link grooves 299. The outer diameter
of the body 203 of the cartridge case 20 is uniform except for the
two annular grooves 299.
[0095] FIG. 20 is a plan view of a cartridge case 20 configured for
linking with a string, in accordance with one embodiment. In the
embodiment shown in FIG. 20, the cartridge case 20a . . . n
comprises two annular string link grooves 299. The string link
grooves 299 are disposed in a recessed portion 295 of the body 203
having an outer diameter smaller than the outer diameter at the
front end and back end of the cartridge case 20. The recessed
portion 295 may aid chambering of the round as the broken string
link sits in the recess 295 and not between the chamber 301 and the
cartridge case 20.
[0096] FIG. 21 is a perspective view of multiple cartridge cases
linked with a string, in accordance with one embodiment. The string
links 297 connect the cartridge case 20 to a preceding and a
subsequent cartridge case 20 thereby forming a belt of ammunition.
Advantageously the belt may be fed from either end.
[0097] While the invention has been described with reference to
certain embodiments, numerous changes, alterations and
modifications to the described embodiments are possible without
departing from the spirit and scope of the invention as defined in
the appended claims, and equivalents thereof.
* * * * *