U.S. patent application number 10/695158 was filed with the patent office on 2005-01-13 for lead free, composite polymer based bullet and cartridge case, and method of manufacturing.
This patent application is currently assigned to Polytech Ammunition Company. Invention is credited to Rembert, William E. III, Wiley, Sy.
Application Number | 20050005807 10/695158 |
Document ID | / |
Family ID | 33567217 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050005807 |
Kind Code |
A1 |
Wiley, Sy ; et al. |
January 13, 2005 |
Lead free, composite polymer based bullet and cartridge case, and
method of manufacturing
Abstract
A lead-free, composite polymer based bullet and cartridge case
and methods of manufacturing the same, wherein the composite
polymer material includes a tungsten metal powder, nylon 6/6, nylon
6, short glass fibers, as well as additives and stabilizers. The
cartridge case includes a lip lock configured to matingly engage a
cannelure formed along an outer circumferential surface of the
bullet. The cartridge case also includes resilient walls wherein
the case may snap fit onto the bullet. The bullet and cartridge
case may be formed in a single step process by injection molding or
a two step process including injection molding and a welding
process.
Inventors: |
Wiley, Sy; (US) ;
Rembert, William E. III; (US) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN
1050 CONNECTICUT AVENUE, N.W.
SUITE 400
WASHINGTON
DC
20036
US
|
Assignee: |
Polytech Ammunition Company
|
Family ID: |
33567217 |
Appl. No.: |
10/695158 |
Filed: |
October 29, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60421782 |
Oct 29, 2002 |
|
|
|
Current U.S.
Class: |
102/517 |
Current CPC
Class: |
B29C 65/0672 20130101;
F42B 12/745 20130101; B29C 65/16 20130101; B29C 65/08 20130101;
B29C 66/71 20130101; B29C 66/73921 20130101; B29C 66/5344 20130101;
B29C 66/7212 20130101; F42B 5/26 20130101; F42B 5/30 20130101; F42B
5/025 20130101; B29L 2031/7772 20130101; B29C 66/612 20130101; B29C
66/1222 20130101; B29C 66/1224 20130101; B29C 65/02 20130101; F42B
5/36 20130101; B29K 2077/00 20130101; B29K 2309/08 20130101; B29C
66/7212 20130101; B29C 66/71 20130101 |
Class at
Publication: |
102/517 |
International
Class: |
F42B 010/00 |
Claims
We claim:
1. A lead-free bullet, comprising: a body made from a composite
polymer material and having a front end and a rear end; a cannelure
formed on an outer circumferential surface of the body intermediate
the front and rear ends of the body, wherein the composite polymer
material includes a tungsten metal powder, nylon 6/6, nylon 6, and
glass fibers; and a specific gravity in a range of 3-10.
2. The bullet according to claim 1, wherein the tungsten metal
powder is 50%-96% of a weight of the bullet body, the nylon 6/6 is
0.5%-15% of the weight of the bullet body, the nylon 6 is 0.5%-15%
of the weight of the bullet body, and wherein the glass fibers are
0.5%-15% of the weight of the bullet body.
3. The bullet according to claim 2, wherein the tungsten metal
powder is 60%-95% of the weight of the bullet body, the nylon 6/6
is 1.0%-12% of the weight of the bullet body, the nylon 6 is
1.0%-12% of the weight of the bullet body, and wherein the glass
fibers are 1.0%-12% of the weight of the bullet body.
4. The bullet according to claim 3, wherein the tungsten metal
powder is 70%-90% of the weight of the bullet body, the nylon 6/6
is 2.0%-9.0% of the weight of the bullet body, the nylon 6 is
2.0%-9.0% of the weight of the bullet body, and wherein the glass
fibers are 2.0%-9.0% of the weight of the bullet body.
5. The bullet according to claim 1, wherein the specific gravity of
the bullet is in the range of 6-9.
6. The bullet according to claim 5, wherein the specific gravity of
the bullet is in the range of 7.5-8.5.
7. The bullet according to claim 1, wherein the tungsten metal
power is encapsulated in the composite polymer material.
8. A lead-free cartridge case capable of holding a bullet having a
cannelure formed along an outer circumferential surface of a body
of the bullet, the cartridge case comprising: a cylindrical body
manufactured from a composite polymer and having a front end and a
rear end opposite the front end; a mouth defined by the front end
of the body; engaging means for engaging the bullet, the engaging
means being disposed along a perimeter of the mouth; a groove
formed along an outer circumferential surface of the body in a
vicinity of the rear end of the body; a web extending radially
inward relative to the body and disposed intermediate the groove
and the mouth, wherein the web separates a bullet holding chamber
located on a front end side of the web from a primer holding
chamber located on a rear end side of the web; and walls of the
body which define the bullet holding chamber and are bendable in a
direction toward and away from a longitudinal axis of the body,
wherein the engaging means are configured to snap fit the cannelure
of the bullet.
9. The cartridge case according to claim 10, wherein the walls
defining the bullet holding cartridge include tapered walls
arranged oblique relative to the longitudinal axis of the body and
straight walls arranged parallel relative to the longitudinal axis
of the body, wherein the tapered walls taper away from the
longitudinal axis of the body in a direction from the rear end to
the front end of the body and transition to the straight walls at a
blend point.
10. The cartridge case according to claim 9, wherein the engaging
means include a lip lock having either one of an asymmetrical
configuration or a symmetrical configuration.
11. The cartridge case according to claim 10, wherein the lip lock
includes a base portion parallel relative to the longitudinal axis
of the body and coinciding with the outer surface of the body, a
tapered portion arranged oblique relative to the longitudinal axis
of the body, and an engaging portion, wherein the engaging portion
is configured to fit within the cannelure of the bullet.
12. The cartridge case according to claim 11, wherein the engaging
portion is either one of parallel or oblique relative to the base
portion.
13. The cartridge case according to claim 8, wherein the groove
defines a rim at the rear end of the body and wherein an outer
diameter of the rim is equal to or less than an outer, diameter of
the rear end of the body.
14. The cartridge case according to claim 8, wherein the groove
defines a rim at the rear end of the body and where in an outer
diameter of the rim is equal to or greater than an outer diameter
of the rear end of the body.
15. The cartridge case according to claim 8, further comprising a
flash hole provided in the web, wherein the bullet holding chamber
communicates with the primer holding chamber through the flash
hole.
16. The cartridge case according to claim 8, wherein the composite
polymer includes a tungsten metal powder, nylon 6/6, nylon 6, glass
fibers, and optionally additives and/or stabilizers.
17. A method for manufacturing a lead-free bullet having a body
made from a composite polymer material including tungsten metal
powder, nylon 6/6, nylon 6, and glass fibers, the method comprising
the following steps: providing a mold configured to a predetermined
caliber bullet; and feeding the composite polymer material through
an injection molding apparatus into the mold.
18. A method for manufacturing a lead-free cartridge case having a
body made from a composite polymer material including tungsten
metal powder, nylon 6/6, nylon 6, and glass fibers, the method
comprising the following steps: providing a mold configured to a
predetermined caliber cartridge case; and feeding the composite
polymer material through an injection molding apparatus into the
mold.
19. A method for manufacturing a lead-free cartridge case having a
body including a case portion and a base portion, each portion
being made from a composite polymer material including tungsten
metal powder, nylon 6/6, nylon 6, and glass fibers, the method
comprising the following steps: providing a mold configured to a
predetermined caliber base portion; providing a mold configured to
a predetermined caliber case portion; feeding the composite polymer
material through an injection molding apparatus into the respective
molds; and welding the formed base portion to the formed case
portion using any one of ultrasonic, spin, or laser welding.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This non-provisional application claims the benefit of U.S.
Provisional patent application Ser. No. 60/421,782, filed Oct. 29,
2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to bullets/projectiles
(hereinafter referred to as bullets) and cartridge cases. More
particularly, the present invention relates to lead free, composite
polymer based bullets and cartridge cases, and a method of
manufacturing the same.
[0004] 2. Description of Related Art
[0005] It is well known in the industry to manufacture bullets and
corresponding cartridge cases from either brass or steel.
Typically, industry design calls for materials that are strong
enough to withstand extreme operating pressures and which can be
formed into a cartridge case to hold the bullet, while
simultaneously resist rupturing during the firing process.
[0006] Conventional ammunition typically includes four basic
components, that is, the bullet, the cartridge case holding the
bullet therein, a propellant used to push the bullet down the
barrel at predetermined velocities, and a primer, which provides
the spark needed to ignite the powder which sets the bullet in
motion down the barrel.
[0007] The cartridge case is typically formed from brass and is
configured to hold the bullet therein to create a predetermined
resistance, which is known in the industry as bullet pull. The
cartridge case is also designed to contain the propellant media as
well as the primer.
[0008] The bullet is configured to fit within an open end or mouth
of the cartridge case and conventionally includes a groove
(hereinafter referred to as a cannelure) formed in the mid section
of the bullet to accept a crimping action imparted to the metallic
cartridge case therein. When the crimped portion of the cartridge
case holds the bullet by locking into the cannelure, a bullet pull
value is provided representing a predetermined tension at which the
cartridge case holds the bullet. The bullet pull value, in effect,
assists imparting a regulated pressure and velocity to the bullet
when the bullet leaves the cartridge case and travels down the
barrel of a gun.
[0009] Furthermore, the bullet is typically manufactured from a
soft material, such as, for example only, lead, wherein the bullet
accepts the mouth of the cartridge being crimped to any portion of
the bullet to hold the bullet in place in the cartridge case, even
though the cartridge case is crimped to the cannelure of the
bullet.
[0010] The propellant is typically a solid chemical compound in
powder form commonly referred to as smokeless powder. Propellants
are selected such that when confined within the cartridge case, the
propellant burns at a known and predictably rapid rate to produce
the desired expanding gases. As discussed above, the expanding
gases of the propellant provide the energy force which launches the
bullet from the grasp of the cartridge case and propels the bullet
down the barrel of the gun at a known and relatively high
velocity.
[0011] The primer is the smallest of the four basic components used
to form conventional ammunition. As discussed above, primers
provide the spark needed to ignite the powder which sets the bullet
in motion down the barrel. The primer includes a relatively s mall
metal cup which contains a priming mixture, foil paper, and
relatively small metal post, commonly referred to as an anvil.
[0012] When a firing pin of a gun or firearm strikes a casing of
the primer, the anvil is crushed to ignite the priming mixture
contained in the metal cup of the primer. Typically, the primer
mixture is an explosive lead styphnate blended with non-corrosive
fuels and oxidizers which burns through a flash hole formed in the
rear area of the cartridge case and ignites the propellant stored
in the cartridge case. In addition to igniting the propellant, the
primer produces an initial pressure to support the burning
propellant and seals the rear of the cartridge case to prevent
high-pressure gases from escaping rearward. It should be noted that
it is well known in the industry to manufacture primers in several
different sizes and from different mixtures, each of which affects
ignition differently.
[0013] The cartridge case, which is typically metallic, acts as a
payload delivery vessel and can have several body shapes and head
configurations, depending on the caliber of the ammunition. Despite
the different body shapes and head configurations, all cartridge
cases have a feature used to guide the cartridge case, with a
bullet held therein, into the chamber of the gun or firearm.
[0014] The primary objective of the cartridge case is to hold the
bullet, primer, and propellant therein until the gun is fired. Upon
firing of the gun, the cartridge case seals the chamber to prevent
the hot gases from escaping the chamber in a rearward direction and
harming the shooter. The empty cartridge case is extracted manually
or with the assistance of gas or recoil from the chamber once the
gun is fired.
[0015] There are three common cartridge case designs that are well
known in the industry. In particular, a bottleneck cartridge case
10 shown in FIG. 1 is used with rifles. A straight inner walled
cartridge case 20 shown in FIG. 2 has inner walls of the cartridge
case that are substantially parallel with a longitudinal axis of
the case, which is commonly used with pistols. A tapered straight
inner walled cartridge case 30 shown in FIG. 3 has inner walls that
are oblique or not parallel relative to the longitudinal axis of
the case and is commonly used with revolvers.
[0016] As shown in FIG. 1, the bottleneck cartridge case 10 has a
body 11 formed with a shoulder 12 that tapers into a neck 13 having
a mouth at a first end. A primer holding chamber 15 is formed at a
second end of the body opposite the first end. A web area 16
separates a main cartridge case holding chamber 17, which contains
a propellant, from the primer holding chamber 15, which communicate
with each other via a flash hole channel 18 formed in the web area
16. An exterior circumferential region of the rear end of the
cartridge case includes an extraction groove 19a and a rim 19b.
[0017] As can be seen in FIG. 2, the straight inner walled
cartridge case 20 does not include a shoulder that tapers to a neck
23 at the first end of the cartridge case 20. Furthermore, the
straight inner walled cartridge case 20 does not have a rim
significantly larger than a case diameter D.sub.20 and is commonly
referred to as a rimless case in the industry. Likewise, the
tapered straight wall cartridge case 30 shown in FIG. 3A differs
from the cartridge case 20 shown in FIG. 2 as it has interior
tapered walls and a rim 39b larger than a case diameter
D.sub.30.
[0018] FIG. 3B is an enlarged view of a lip lock 32 provided in the
vicinity of the mouth 34 of the cartridge case 30. The lip lock 32
includes a first, generally straight portion 32a, which is
orthogonal to a longitudinal axis of the case 30; a second,
generally straight portion 32b, which is parallel to the
longitudinal axis of the case 30 and orthogonal to the first
straight portion 32a; and a slanted portion 32c, which is oblique
relative to the longitudinal axis of the cartridge case 30 and both
straight portions 32a and 32b. The lip lock 32 is used to securely
grip a bullet (not shown).
[0019] Typically, manufacturers must take as many as twenty three
(23) steps to manufacture a brass cartridge case from a rolled
strip of brass material. During loading, which is the step where
the cartridge case is loaded with the powder and bullet, the brass
cartridge case is crimped to the bullet so that the bullet is held
therein. It is well understood that crimping is necessary to assist
in creating the pressure needed for satisfactory ballistic
performance.
[0020] Ballistic performance is a set of measurable events
resulting from the combination of a particular bullet weight placed
over a particular propellant charge to be ignited by a priming
method of predetermined size that establishes the pressure build up
needed to propel the bullet at a desired velocity.
[0021] As shown in the schematic diagram of FIG. 4, case walls 41a
and 41b of the brass cartridge cases 40 are typically crimped at a
mouth 44 onto the bullet B to hold the bullet B in place. The
contact surface is the wall thickness of the brass cartridge case
40 at the point the cartridge case 40 is crimped.
[0022] Alternatively, the cartridge case 50 may be tapered from a
rear end 51 to the mouth 54, as shown in FIG. 5, so as to create a
press fit P at the mouth 54 of the case 50, which causes the bullet
B to be held in place over a larger bearing surface.
[0023] In yet another alternative, adhesives may be used to hold
the cartridge case and bullet assembly together to assist in
providing a desired pressure. Some commercial, law enforcement, and
military firearms ammunitions are assembled with adhesives to
provide an increased pressure where a simple crimping step is not
sufficient.
[0024] In the late 1990's it was reported that the military would
begin the use of so-called green bullets. Supposedly, such green
bullets would be made of high-density materials, such as tungsten,
mixed with lighter materials, such as tin and zinc. It was also
reported that tungsten-nylon cores could be used. However, no
specific range of ingredients was ever provided. It should be noted
that the green bullets were fabricated with copper jackets. See
Mikko, Assoc. of Firearm and Tool Mark Exam. Journ., vol. 31, No.
4, Fall 1999; USA Today, "`Green` Army bullets to get the lead
out," and Environmental Update, Fall 1999.
[0025] Several patents for green bullets have been issued.
[0026] For example, WO 88/09476 to Booth discloses a bullet made of
materials having a specific gravity of 3 to 7, a matrix of plastic
material, such as nylon 6 or nylon 6/6, and a filler of a finely
divided metal, such as copper, bronze or tungsten. In the preferred
compositions, Nylon is incorporated in an amount of 8% or 11% by
weight. The filler material is present in essentially the remainder
amount. Either one of the nylon 6/6 or nylon 6 is explained as
being used in amounts of up to 20% by weight. Booth does not
disclose using both nylon materials together in the same
bullet.
[0027] U.S. Pat. No. 5,616,642 to West et al. discloses a bullet
containing a high density powder, such as copper, tungsten,
bismuth, ceramic or stainless steel, i n an amount of at least 85%,
dispersed in a polyester matrix, such as polybutylene terephthalate
or polyethylene terephthalate.
[0028] U.S. Pat. No. 6,048,379 to Bray et al. discloses a bullet
made of tungsten, a fiber, such as stainless steel, copper,
aluminum, nylon, Kevlar, Spectra, nickel, glass or carbon, and a
binder material, such as nylon 12 or a polyester elastomer. Bray et
al. indicate nylon 6/6 and nylon 6 are resins that are not suitable
as binders. See column 10, lines 18-19.
[0029] U.S. Pat. No. 6,257,149 to Cesaroni discloses a bullet
having a core made of a polymer, such as ethylene/methacrylic acid
copolymer ionomers, polyetherester elastomers or polyamides, such
as nylon 11 or nylon 12, and a jacket made of copper, nylon 6/6,
nylon 6/12, nylon 4/12, flexible nylon, nylon 6 or nylon 11.
[0030] As stated above, the test for all methods of holding the
bullet within a cartridge case is commonly known as bullet pull.
The Sporting Arms and Ammunition Manufactures Institute
(hereinafter referred to as "S.A.A.M.I.") established a bullet pull
for all calibers that creates a desired pressure to deliver the
desired ballistics. The United States Military has also established
bullet pull specifications that achieve the products desired
ballistic performance.
SUMMARY OF THE INVENTION
[0031] It is an aspect of the present invention to provide a
bullet, a cartridge case, and method of manufacturing the same that
overcome the drawbacks of the conventional brass or lead bullets,
cartridge case, and laborious, yet required, methods of
manufacturing given the material compositions of the same.
[0032] In particular, it is an aspect of the present invention to
provide a lead free, composite polymeric bullet and cartridge case,
and method of manufacturing the same by injection molding requiring
one or two steps, dependent on the cartridge caliber, to
manufacture the cartridge case as opposed to the twenty three steps
commonly needed to prepare the conventional brass cartridge cases.
Furthermore, the present invention also manufactures bullets in a
single step by injection molding, as opposed to as many as six (6)
steps needed to manufacture the conventional lead based
bullets.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Other aspects and features of the present invention will be
better understood from the following description, with reference to
the accompanying drawings, wherein:
[0034] FIG. 1 is a cross sectional view of a conventional
bottleneck cartridge case used with rifles;
[0035] FIG. 2 is a cross sectional view of a straight walled
rimless cartridge case used with pistols;
[0036] FIG. 3A is a cross sectional view of a tapered straight
walled cartridge case having a rim and used with revolvers;
[0037] FIG. 3B is an enlarged view of a lip lock provided near a
mouth of the cartridge case illustrated in FIG. 3;
[0038] FIG. 4 is a schematic diagram illustrating how a
conventional cartridge case is bent in the mouth region to hold the
bullet therein;
[0039] FIG. 5 is a schematic diagram illustrating how a
conventional cartridge case is tapered from the base of the case to
the mouth region to press fit the case onto the bullet;
[0040] FIG. 6 is a cross sectional view of a cartridge case
according to a first embodiment of the present invention;
[0041] FIG. 7 is an enlarged view of the lip lock of the cartridge
case shown in FIG. 6;
[0042] FIG. 8 is a cross sectional view of the cartridge case shown
in FIG. 6 holding a corresponding caliber bullet;
[0043] FIG. 9 is a cross sectional view of a cartridge case
according to a second embodiment of the present invention;
[0044] FIG. 10 is a an enlarged view of the lip lock o f t he
cartridge case shown in FIG. 9;
[0045] FIG. 11 is a cross sectional view of the cartridge case
shown in FIG. 9 holding a corresponding caliber bullet;
[0046] FIG. 12 is a table of a ballistic chart; and
[0047] FIGS. 13A-C illustrate a method for producing an all-polymer
injection molded cartridge case.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0048] The present invention provides a cartridge case body strong
enough to withstand gas pressures that equal or surpass the
strength of brass cartridge cases under certain conditions.
Furthermore, the present invention provides a lead free, composite
polymer based bullet having a specific gravity high enough to
perform as well as if not better than conventional lead based
bullets.
[0049] FIG. 6 illustrates a first embodiment of the invention. In
particular, a cartridge case 60 for holding a 0.45 caliber bullet
therein is shown. The cartridge case satisfies S.A.A.M.I.
requirements for 0.45 caliber ammunition.
[0050] For example, the cartridge case 60 has a front end that
holds the bullet (not shown) and a rear end that holds the primer.
A length I of the cartridge case 60 from a front end face 61 to a
rear end face 62 ranges from about 0.888 in. to 0.898 in., and
preferably is about 0.894 in. An outer diameter D.sub.M of the
cartridge case 60 at a mouth 63 is about 0.467 in. to 0.473 in.,
and preferably is about 0.470 in. and an outer diameter D.sub.P at
a rear end 64 of the cartridge case 60 is about 0.469 in. to 0.476
in. and preferably is about 0.471 in.
[0051] The rear end 64 of the cartridge case 60 has a groove 65
formed therein with a thickness G.sub.T that ranges from about
0.036 in. to 0.39 in., and preferably is about 0.38 in. and a depth
G.sub.D that ranges from about 0.037 in. to 0.043 in., and
preferably is about 0.040 in. (see FIG. 8) The groove 65 defines a
rim 66 at the most rearward point of the cartridge case 60, wherein
the rim 66 has an outer diameter D.sub.R that ranges between about
0.470 in. and 0.476 in., and preferably is about 0.474 in. and a
width W.sub.R that ranges between about 0.039 in. and 0.049 in.,
and preferably is about 0.045 in.
[0052] Radially inward relative to the groove 65 is a primer
holding chamber 66, which has an outer diameter D.sub.PC that
ranges from about 0.203 in. to 0.210 in., and is preferably about
0.207 in. and a depth dpc that ranges from about 0.115 in. to 0.120
in., and preferably is about 0.117 in.
[0053] A bullet holding chamber 67 and the primer holding chamber
66 define a web 68 in the portion of a cartridge case body 69
therebetween, wherein the web 68 has a thickness W.sub.T that
ranges between about 0.047 in. and 0.100 in., and preferably is
about 0.050 in. The primer holding chamber 66 communicates with the
bullet holding chamber 67 via a flash hole 70 formed in the web 68,
wherein the flash hole 70 has an outer diameter D.sub.FH that
ranges between about 0.077 in. to 0.83 in., and preferably is about
0.80 in.
[0054] As shown in FIG. 6, the cartridge case 60 has a
substantially cylindrical configuration with inner walls 71, 71
that taper from a rear end 72 of the bullet chamber 67 toward the
mouth 63 located at the front end of the bullet chamber 67. The
taper of the cartridge case inner walls 71, 71 transitions to walls
73, 73 that are parallel relative to a longitudinal axis x-x of the
cartridge case 60. The transition occurs at a region of the case
that is intermediate relative to the rear and front ends of the
bullet chamber 67 and is referred to as a blend point 74.
[0055] As shown in FIG. 6, a lip lock 75 is located at the most
forward point of the cartridge case body 69 to define the mouth 63
of the cartridge case 60. The lip lock 75 holds the bullet (not
shown) in the cartridge case 60.
[0056] FIG. 7 shows an enlarged view of the lip lock 75, which has
a base portion 75a that coincides with the outer surface of the
cartridge case and is about 0.010 in. to 0.030 in. in length, and
preferably is about 0.020 in. in length. The lip lock 75 has a
unique configuration which is variable from an asymmetrical shape
having a tapered rearward portion (as shown) to various symmetrical
configurations depending on the desired bullet holding
requirements. A taper portion 75b of the lip lock 75 has a
thickness that is about 0.010 in. and a width that ranges from
about 0.020 in. at the widest portion to a width that corresponds
to the length of the engaging portion. An engaging portion 75c of
the lip lock 75 has a length leg ranging from about 0.008 in. to
0.012 in., and preferably is about 0.010 in.
[0057] It should be noted that the engaging portion 75c of the lip
lock 75 should have a length leg that does not exceed the overall
width of a cannelure formed in the bullet (not shown), which will
be described below, such that the engaging portion 75c of the lip
lock 75 is able to fit within the bullet lip lock cannelure.
Furthermore, although not required, it is preferable that the base
portion 75a of the lip lock 75 is parallel relative to the engaging
portion 75c, but it is within the scope of this invention to
arrange the engaging portion 75c to be oblique relative to the base
portion 75a.
[0058] The cartridge case 60 and bullet are manufactured by an
injection molding process from a composite polymer by feeding the
polymer through an injection molding apparatus. Because the
cartridge case 60 is manufactured from a composite polymer, the
walls of the cartridge case 60 from the mouth 63 to the blend 74
are able to be bent either radially inward toward the longitudinal
axis x-x of the case or radially outward away from the longitudinal
axis x-x. The flexibility of the case walls permit the mouth 63 to
be temporarily expanded to receive the corresponding bullet, which
is also manufactured from a composite polymer that may or may not
be the same as the composite polymer used to manufacture the
cartridge case. Properly prepared with the correct corresponding
groove, conventional lead or jacketed bullets can be used with the
polymer cartridge case design described herein.
[0059] Once the mouth 63 is expanded, the corresponding bullet B is
inserted therein. It should be noted that the bullet B has an outer
diameter D.sub.B that ranges between 0.450 in. to 0.453 in., and
preferably is 0.451 in. (see FIG. 6) Furthermore, the bullet B
(FIG. 8) has a cannelure 80 formed on an outer circumferential
surface at a location that permits the engaging portion 75c of the
lip lock 75 to be inserted therein and wherein the bullet B is not
inserted beyond the blend 74 on the inner walls 71, 71 of the case
body 69.
[0060] Accordingly, the bullet is inserted into the bullet holding
chamber 67 of the cartridge case 60 by slightly expanding the mouth
63 until the bullet cannelure 80 coincides with the engaging
portion 75c of the lip lock 75. The lip lock 75 is then permitted
to snap back to an original position wherein the engaging portion
75c of the lip lock 75 matingly engages the cannelure 80 of the
bullet B. See FIG. 8. The lip lock 75 provides enough resistance to
provide the required bullet pull value of approximately 5 to 20
pounds, which is greatly reduced from conventional bullet pull
values for brass cartridge cases, which are approximately 35 to 65
pounds. U.S. Military Specifications require a higher bullet pull
in some cases to assure that certain Legacy Weapons Systems will
fully function properly. In these cases, the bullet pull of this
invention can be increased to accommodate any U.S. Military Weapon
Systems.
[0061] The lip lock 75 also prevents creeping of the bullet. Creep
occurs when a bullet moves forward in its case due to recoil
generated by the firing of adjacent cartridges. In a semi-automatic
pistol, creep can cause cartridges to jam in the magazine and/or
prevent proper feeding into the chamber due to excessive overall
length, which would render the pistol inoperable.
[0062] As shown in FIG. 8, the overall length l.sub.60 of the
cartridge case 60 and bullet B held therein ranges from about 1.190
in. to 1.270 in. and is preferably about 1.263 in. in length.
Furthermore, when the firearm is fired, the lip lock 75 permits the
smooth release of the bullet B, which enhances the accuracy of the
firearm.
[0063] The present invention is not limited to the above-described
caliber and is believed to be applicable to other calibers as well.
For example, FIGS. 9-11 show a second embodiment of the invention,
and in particular, a cartridge case 100 for holding a 38 special
caliber bullet. The cartridge case 100 satisfies S.A.A.M.I.
requirements for 38 special caliber ammunition.
[0064] A length l' of the cartridge case 100 from a front end face
161 to a rear end face 162 ranges from about 1.135 in. to 1.155
in., and preferably is about 1.154 in. An outer diameter D.sub.100
of the cartridge case 100 at a mouth 163 is about 0.372 in. to
0.379 in., and preferably is about 0.374 in. and an outer diameter
D.sub.P2 at a primer end is about 0.372 in. to 0.376 in. and
preferably is about 0.374 in.
[0065] A rear end 164 of the cartridge case 100 has a rim 166
formed thereon, wherein the rim 166 has an outer diameter D.sub.R2
that ranges between about 0.428 in. and 0.440 in., and preferably
is about 0.433 in. and a width W.sub.R2 that ranges between about
0.048 in. and 0.059 in., and preferably is about 0.056 in.
[0066] Radially inward relative to a groove 165 is a primer holding
chamber 166, which has an outer diameter D.sub.PC2 that ranges from
about 0.168 in. to 0.175 in., and is preferably about 0.171 in. and
a depth that ranges from about 0.115 in. to 0.120 in., and
preferably is about 0.117 in.
[0067] A bullet holding chamber 167 and the primer holding chamber
166 define a web 168 in the portion of the cartridge case body
therebetween, wherein the web 168 has a thickness that ranges
between about 0.047 in. and 0.100 1 in, and preferably is about
0.050 in. The primer holding chamber 166 communicates with the
bullet holding chamber 167 via a flash hole 170 formed in the web
168. The flash hole 170 has an outer diameter D.sub.FH2 that ranges
between about 0.077 in. to 0.83 in., and preferably is about 0.80
in. (see FIG. 11)
[0068] As shown in FIG. 9, the cartridge case 100 has a
substantially cylindrical configuration with inner walls 171 that
taper from a rear end 172 of the bullet holding chamber 167 toward
the mouth 163 located at the front end of the case. The taper of
the cartridge case inner walls 171 transitions to walls that are
parallel relative to the longitudinal axis of the cartridge case
100. The transition occurs at a region of the case intermediate
relative to the rear end 172 and mouth 163 of the case 100 and is
referred to as a blend point 174.
[0069] As shown in FIG. 9, a lip lock 175 is located at the most
forward point of the cartridge case body and defines the mouth 163
of the cartridge case 100. The lip lock 175 holds the bullets in
the cartridge case 100. The lip lock 175 also prevents creeping of
the bullets. Creep occurs when the bullet S moves forward in the
case 100 due to recoil caused by firing of adjacent cartridges. In
a revolver, creep will allow the bullet to protrude out of the
cylinder, preventing its rotation (causing a jam), thus rendering
the firearm inoperable.
[0070] FIG. 10 shows an enlarged view of the lip lock 175, which
has a base portion 175a that coincides with the outer surface of
the cartridge case 100 and is about 0.018 in. to 0.022 in. in
length, and preferably is about 0.020 in. in length. The lip lock
175 has a taper portion 175b that tapers from the base portion 175a
to an engaging portion 175c, wherein the taper portion 175b has a
thickness that is about 0.010 in. and a width that ranges from
about 0.020 in. at the widest portion to a width that corresponds
to the length of the engaging portion 175c. The engaging portion
175c has a length ranging from about 0.008 in. to 0.012 in., and
preferably is about 0.010 in.
[0071] Once the mouth 163 is expanded, the corresponding bullet S
is inserted therein. It should be noted that the bullet S has an
outer diameter that ranges between about 0.355 in. to 0.359 in.,
and preferably is about 0.357 in. Furthermore, the bullet S has a
cannelure 180 formed on an outer circumferential surface at a
location that permits the engaging portion 175c of the lip lock 175
to be inserted therein.
[0072] Accordingly, the bullet S is inserted into the bullet
holding chamber 167 until the bullet cannelure 180 coincides with
the engaging portion 175c of the lip lock 175. The lip lock 175 is
then permitted to snap back to an original position wherein the
engaging portion 175c of the lip lock 175 matingly engages the
bullet cannelure 180. (See FIG. 11) The lip lock 175 provides
enough resistance to provide a bullet pull of about 5 to 20 pounds
which is greatly reduced from conventional bullet pull values for
brass cartridge cases, which is about 35 pounds. An overall length
l.sub.100 of the cartridge case 100 and bullet S held therein
ranges from about 1.400 in. to 1.550 in. and is preferably about
1.531 in. in length. Furthermore, when the firearm is fired, the
lip lock 175 permits the smooth release of the bullet S, which
enhances the accuracy of the firearm.
[0073] As stated above, the cartridge case and bullet are
manufactured by feeding a composite polymer through an injection
molding machine into molds configured to the particular geometric
shapes of the case and caliber of bullet, respectively. In other
words, the entire and complete cartridge case is manufactured or
molded in a single operation. Furthermore, the entire and complete
bullet is manufactured or molded in a single operation. The
dimensions for the molds are selected to allow the proper shrinkage
of the composite polymer material to achieve the desired
specifications and/or caliber. As shown in the table of FIG. 12,
the cartridge case is strong enough to provide the same pressure
retention benefits as brass cartridge cases, and when the same
propellant is used, the lead free, composite polymer cartridge case
of the present invention delivers the same velocities as brass
cartridge cases, but at a substantially lower pressure curve. Also,
as stated above, compared to conventional brass case cartridges,
the lead free, composite polymer cartridge case of the present
invention provides bullet pull values that are 700% to 1400%
less.
[0074] A first embodiment of the lead free, composite polymer
material is suitable for the bullet. The polymer material includes,
by weight, a tungsten metal powder in the range of about 50-96%,
preferably about 60-95%, and most preferably about 70-90%, of the
overall composition of the polymer material. It is most suitable
that the tungsten metal powder be present in at least 70% by
weight. The polymer material also includes about 0.5-15%,
preferably about 1-12%, and most preferably about 2-9% by weight,
of nylon 6/6, about 0.5-15%, preferably about 1-12%, and most
preferably about 2-9% by weight, of nylon 6, and about 0.5-15%,
preferably about 1-12%, and most preferably about 2-9% by weight,
of glass fibers. It is most suitable that each of these ingredients
be included in amounts less than 10% by weight.
[0075] The polymer material according to the first embodiment
preferably has a specific gravity of 3-10, more preferably 6-9, and
most preferably 7.5-8.5. Preferably, the polymer material has a
specific gravity which permits the molded bullet to provide a user
with a point of aim that is comparable to that of the conventional
lead products. A bullet formed in accordance with the present
invention is environmentally friendly as it does not have any lead,
performs ballistically similar to conventional bullets, has a lower
weight while using the same firearm hold characteristics, and can
be produced at a substantially lower manufacturing cost.
Furthermore, the composite polymer material of the first embodiment
preferably encapsulates the tungsten powder such that the composite
polymer bullet does not wear down the barrel of the firearm, which
results in a longer life for the firearm.
[0076] The properties of the selected polymer material provide
several advantages over the conventionally used brass and lead
materials used for cartridge cases and bullets, respectively. For
example, the polymer material provides a way for the cartridge case
to hold the bullet that replaces crimping and eliminates a need to
use adhesives in cases where adhesives are required to provide the
proper bullet pull properties when using brass cases. The unique
lip lock design permits the cartridge case to be snapped into the
corresponding cannelure of the bullet.
[0077] Brass cartridge cases tend to form to the chamber walls when
fired. In contrast, the composite polymer cartridge case of the
present invention flexes during firing, but the material memory
returns the cartridge case to its original dimensions. Accordingly,
the combination of the composite polymer material returning to its
original dimension after firing, the lubricity of the polymer aid
extraction in contrast to brass, which ultimately inhibits
extraction.
[0078] FIGS. 13A-C illustrate a method for producing an
all-polymer, injection molded bottleneck cartridge case 200,
wherein FIG. 13A illustrates a base 210, FIG. 13B illustrates a
case 230, and FIG. 13C illustrates the case 200 after assembly. The
bottleneck shaped case is produced by molding two separate parts,
i.e., a case body 231 having a bottleneck configuration, and a base
210. The base 210 includes a rim 211 defining an extractor groove
212 having a ramp 213. A web 214 defines a flash hole 215
therethrough, wherein the flash hole 215 leads to a primer holding
chamber 216.
[0079] The base 210 and case 230 are welded together in a secondary
production operation. In order to achieve a strong weld, the base
210 and case 230 must have a weld joint profile 216 and 232,
respectively, molded into each of the two parts. The weld joint
profiles are designed to accommodate a welding process, which can
include ultrasonic, spin or laser welding. The welding procedure
will be dictated by the choice of polymer material for the
cartridge being manufactured. An important design feature of the
base 210 is the thickness of the web 214. In some types of
firearms, the chamber does not fully support the base end of the
cartridge case. In order to maximize the strength of the base in
this area, the flash hole channel of the present invention can be
extended by making the web 214 relatively wider. Consequently, such
a design allows the explosive force of the primer and gunpowder
ignition to take place in the area of the chamber where the case is
fully supported.
[0080] Many modifications may be made to adapt the teachings of
this invention to particular situations or materials without
departing from the scope thereof. Therefore, this invention should
not be limited to the particular embodiments disclosed herein, but
includes all embodiments within the spirit and scope of the
disclosure.
* * * * *