U.S. patent application number 13/350585 was filed with the patent office on 2012-07-19 for high strength polymer-based cartridge casing for blank and subsonic ammunition.
This patent application is currently assigned to PCP AMMUNITION COMPANY LLC. Invention is credited to Charles Padgett, Sy Wiley.
Application Number | 20120180687 13/350585 |
Document ID | / |
Family ID | 45563546 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120180687 |
Kind Code |
A1 |
Padgett; Charles ; et
al. |
July 19, 2012 |
HIGH STRENGTH POLYMER-BASED CARTRIDGE CASING FOR BLANK AND SUBSONIC
AMMUNITION
Abstract
A high strength polymer-based cartridge casing includes an upper
component of polymer having a first end with a mouth, at least a
wall between the first end and a second end of the upper component
opposite the first end, a sleeve extending longitudinally and
radially about the wall, and at least one of an overlap portion and
an underskirt portion extending from the wall near the second end.
The lower component is molded from a polymer and includes at least
one of a tapered portion and an outer tapered portion that engages
at least one of the overlap portion and the underskirt portions,
respectively, to join the upper and the lower components. Further,
the sleeve reduces a volume of a propellant chamber formed by the
wall. The reduced volume of the propellant chamber permits only
enough propellant to propel a bullet engaged in the cartridge
casing at subsonic speeds.
Inventors: |
Padgett; Charles; (Orlando,
FL) ; Wiley; Sy; (Orlando, FL) |
Assignee: |
PCP AMMUNITION COMPANY LLC
ORLANDO
FL
|
Family ID: |
45563546 |
Appl. No.: |
13/350585 |
Filed: |
January 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61433170 |
Jan 14, 2011 |
|
|
|
Current U.S.
Class: |
102/466 |
Current CPC
Class: |
F42B 5/313 20130101 |
Class at
Publication: |
102/466 |
International
Class: |
F42B 5/30 20060101
F42B005/30 |
Claims
1. A high strength polymer-based cartridge casing for at least one
of blank or subsonic ammunition comprising: an upper component,
molded from a polymer, comprising: a first end having a mouth; at
least a wall between the first end and a second end of the upper
component opposite the first end; a sleeve extending longitudinally
and radially about the wall; and at least one of an overlap portion
and a underskirt portion extending from the wall near the second
end; a lower component, molded from a polymer, comprising: at least
one of a tapered portion and an outer tapered portion that engages
at least one of the overlap portion and the underskirt portions,
respectively, to join the upper and the lower components; wherein
the sleeve reduces a volume of a propellant chamber formed by the
wall.
2. The high strength polymer-based cartridge casing of claim 1,
wherein the reduced volume of the propellant chamber permits only
enough propellant to propel a bullet engaged in the cartridge
casing at subsonic speeds.
3. The high strength polymer-based cartridge casing of claim 1,
wherein the upper component further comprises: an extension engaged
at the mouth; and a cap engaged to an end of the extension opposite
the mouth; wherein the cap elastically deforms when the cartridge
is fired.
4. The high strength polymer-based cartridge casing of claim 1,
wherein a length of the upper component is greater than a length of
the lower component.
5. The high strength polymer-based cartridge casing of claim 1,
wherein a length of the lower component is greater than a length of
the upper component.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 61/433,170 filed Jan. 14, 2011. The
provisional application is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present subject matter relates to techniques and
equipment to make ammunition articles and, more particularly, to
ammunition articles with plastic components such as cartridge
casing bodies and bases for at least blank and subsonic
ammunition.
BACKGROUND
[0003] 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.
[0004] 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.
[0005] 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.
[0006] However, brass is heavy, expensive, and potentially
hazardous. For example, the weight of 0.50 caliber ammunition is
about 60 pounds per box (200 cartridges plus links).
[0007] 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.
[0008] 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.
[0009] However, one drawback of this design is that the crimped
neck does not release from around the bullet evenly when fired.
This leads to uncertain performance from round to round. Pressures
can build up unevenly and alter the accuracy 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 that 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 that sets the bullet
in motion down the barrel. The primer includes a relatively small
metal cup containing 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] As shown in FIG. 1A, a 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 divider 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.
[0016] Prior art patents in this area include U.S. Pat. No.
4,147,107 to Ringdal, U.S. Pat. No. 6,845,716 to Husseini et al.,
U.S. Pat. No. 7,213,519 to Wiley et al., and U.S. Pat. No.
7,610,858 to Chung. The four patents are directed to an ammunition
cartridge suitable for rifles or guns and including a cartridge
case made of at least a plastics material. However, each have their
own drawbacks.
[0017] Further, the use of brass cartridges for blank or subsonic
ammunition can be problematic. To reduce the velocity of the bullet
exiting the cartridge, typically less propellant is used is
comparison to when the bullet is traveling at its top velocity.
However, the same size cartridge needs to be used so the bullet can
be fired from a standard firearm. An empty space is left inside a
blank or subsonic cartridge where the propellant would normally
reside. To compensate, wadding (typically cotton) can be packed
into the space normally filled by the propellant. This wadding can
cause problems with the use of the round, including jamming the
firearm and fouling silencers and/or suppressors attached to the
firearm.
[0018] Hence, a need exists for a polymer casing that can perform
as well as or better than the brass alternative. A further
improvement are polymer casings that are capable of production in a
more conventional and cost effective manner, i.e. by using standard
loading presses. Additionally, the cartridge can provide increased
performance for blank and subsonic rounds.
SUMMARY
[0019] The teachings herein alleviate one or more of the above
noted problems with the strength and formation of polymer based
cartridges.
[0020] Thus, a high strength polymer-based cartridge casing can
include an upper component, molded from a polymer, and having a
first end with a mouth, at least a wall between the first end and a
second end of the upper component opposite the first end, a sleeve
extending longitudinally and radially about the wall, and at least
one of an overlap portion and an underskirt portion extending from
the wall near the second end. The lower component is molded from a
polymer and includes at least one of a tapered portion and an outer
tapered portion that engages at least one of the overlap portion
and the underskirt portions, respectively, to join the upper and
the lower components. Further, the sleeve reduces a volume of a
propellant chamber formed by the wall. The reduced volume of the
propellant chamber permits only enough propellant to propel a
bullet engaged in the cartridge casing at subsonic speeds or less,
if it is a blank cartridge.
[0021] Alternately, the upper component of the high strength
polymer-based cartridge casing can further include an extension
engaged at the mouth and a cap engaged to an end of the extension
opposite the mouth. In an example, the cap elastically deforms when
the cartridge is tired.
[0022] As a result, a light weight, high strength cartridge case
can be formed using standard brass cartridge loading equipment. As
noted below, the present invention can be adapted to any type of
cartridge, caliber, powder load, or primer. Calibers can range at
least between 0.22 and 30 mm and accept any type of bullet that can
be loaded in a typical brass cartridge.
[0023] Further advantages can be gained in both blank and subsonic
ammunition due to the removal of wadding and the shrinking of the
volume of powder based on a reduced volume in the cartridge.
[0024] The polymer used can be of any known polymer and additives,
but the present invention uses a nylon polymer with glass fibers.
Further, the portion of the cartridge that engages the extractor of
the firearm can be made from heat strengthened steel for normal
loads and can be a continuous molded polymer piece of the lower
component for either subsonic or blank ammunition.
[0025] Additional advantages and novel features will be set forth
in part in the description which follows, and in part will become
apparent to those skilled in the art upon examination of the
following and the accompanying drawings or may be learned by
production or operation of the examples. The advantages of the
present teachings may be realized and attained by practice or use
of various aspects of the methodologies, instrumentalities and
combinations set forth in the detailed examples discussed
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The drawing figures depict one or more implementations in
accord with the present teachings, by way of example only, not by
way of limitation. In the figures, like reference numerals refer to
the same or similar elements.
[0027] FIG. 1A is a cross sectional view of a conventional
bottleneck cartridge case;
[0028] FIG. 1B is a side view of a conventional bullet;
[0029] FIG. 2 is a side perspective view of the outside of
cartridge case of the present invention;
[0030] FIG. 3 is a longitudinal cross-section of the upper
component of the cartridge;
[0031] FIG. 4 is a bottom, side, perspective, radial cross-section
of the upper and lower components of the cartridge;
[0032] FIG. 5 is an end view of the upper component without the
lower component and insert;
[0033] FIG. 6 is a side view of the lower component without the
upper component and insert;
[0034] FIG. 7 is a bottom front perspective view of the lower
component of FIG. 6;
[0035] FIG. 8 is a longitudinal cross-section view of the lower
component of FIG. 6
[0036] FIG. 9 is a side view of the insert without the upper and
lower components;
[0037] FIG. 10 is a bottom front perspective view of the insert of
FIG. 8;
[0038] FIG. 11 is a longitudinal cross-section view of the insert
of FIG. 8;
[0039] FIG. 12 is a longitudinal cross-section view of an example
of a cartridge case;
[0040] FIG. 13 is a top, side, perspective view of the upper
component of the example;
[0041] FIG. 14 is a top, side perspective view of an example of an
upper component of a subsonic cartridge;
[0042] FIG. 15 is a top, side perspective view of an upper
component for a blank cartridge;
[0043] FIG. 16 is a longitudinal cross-section view of an example
of a straight wall cartridge case; and
[0044] FIG. 17 is a longitudinal cross-section view of the
cartridge case of FIG. 2.
DETAILED DESCRIPTION
[0045] In the following detailed description, numerous specific
details are set forth by way of examples in order to provide a
thorough understanding of the relevant teachings. However, it
should be apparent to those skilled in the art that the present
teachings may be practiced without such details. In other
instances, well known methods, procedures, components, and/or
circuitry have been described at a relatively high-level, without
detail, in order to avoid unnecessarily obscuring aspects of the
present teachings.
[0046] 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, e.g.
for both storage and handling.
[0047] Reference now is made in detail to the examples illustrated
in the accompanying drawings and discussed below. FIG. 2
illustrates an example of a cartridge case 100. The cartridge case
100 includes an upper component 200, a lower component 300, and an
insert 400. In this example, the upper component 200 and the lower
component 300 are made of a polymer, while insert 400 is made from
a metal, an alloy of metals, or an alloy of a metal and a
non-metal. Regardless of materials, the outer dimensions of the
cartridge case 100 are within the acceptable tolerances for
whatever caliber firearm it will be loaded into.
[0048] The polymer used is lighter than brass. A glass-tilled high
impact polymer can be used where the glass content is between
0%-50%, preferably between 5% and 50%. In another example the glass
content can be 10%. An example of a high impact polymer without the
glass content is BASF's Capron.RTM. BU50I. The insert 400 can be
made of steel, and, in an example, heat treated carbon steel, 4140.
The 4140 steel is further heat treated to a Rockwell "C" scale
("RC") hardness of about 20 to about 50. However, any carbon steel
with similar properties, other metals, metal alloys or
metal/non-metal alloys can be used to form the insert. Heat
treating a lower cost steel alloy to improve its strength is a
point of distinction from the prior art, which have typically opted
for more expensive alloys to deal with the strength and ductility
needed for a cartridge casing application.
[0049] In an example, the combination of the upper component 200
and the lower component 300 are made of 10% glass-filled high
impact polymer combined with the insert 400 made of heat treated
4140 steel results in a cartridge that is approximately 50% lighter
than a brass formed counterpart. This weight savings in the
unloaded cartridge produces a loaded cartridge of between 25%-30%
lighter than the loaded brass cartridge depending on the load used,
i.e. which bullet, how much powder, and type of powder used.
[0050] The upper component 200 includes a body 202 which
transitions into a shoulder 204 that tapers into a neck 206 having
a mouth 208 at a first end 210. The upper component 200 joins the
lower component 300 at an opposite, second end 212. The lower
component 300 joins the upper component 200 at a lower component
first end 302 (see FIG. 6). The upper 200 and lower 300 components
are adhered by an ultraviolet (UV) light or heat cured resin, a
spin weld, a laser weld or an ultrasonic weld.
[0051] At a second end 304 of the lower component 300, the lower
component is joined to the insert 400. In one example, the upper
component 200 and the lower component 300 are molded in separate
molds. When the lower component 300 is molded, it is molded over
the insert 400. This is a partial molding over, since the lower
component 300 does not completely cover the insert 400.
[0052] A back end 402 of the insert 400 is also the rear end of the
casing 100. The insert 400 is formed with an extraction groove 404
and a rim 406. The groove 404 and rim 406 are dimensioned to the
specific size as dictated by the caliber of the ammunition. The
insert 400 can be formed by turning down bar stock to the specific
dimensions or can be cold formed.
[0053] Turning now to FIG. 3, a cross-section of the upper
component 200 is illustrated. Because of the nature of the polymer,
and the design of the neck 206 and mouth 208, the neck 206 expands
uniformly under the gas pressures formed during firing. This
concentric expansion provides a smoother release of the projectile
into the barrel of the firearm. The smoother release allows for a
more stable flight of the projectile, providing greater accuracy
and distance with the same amount of powder.
[0054] Moving toward the second end 212 of the upper component 200,
as the neck 206 transitions into the shoulder 204, a sleeve 230
begins. The sleeve 230, in this example, extends approximately to
the second end 212. The sleeve 230 can be an additional thickness
to a wall 218 as is normally required for a standard cartridge, or
a separately manufactured and adhered to the wall 218. The sleeve
230 provides additional strength relative to the wall 218 of the
body 202 alone. This strengthening, which is in the lateral
direction, reduces bending of the upper component 200 of the
cartridge case 100. The sleeve 230 helps to keep the cartridge 100
as concentric as possible, and as noted above, concentricity is a
key to accuracy.
[0055] The case wall 218 can have a thickness T, and the sleeve 230
can have a thickness T+, as illustrated in FIG. 4. Thus, the total
thickness of the cartridge at the point where there is the wall 218
and sleeve 230 is the sum of T and T+.
[0056] The upper portion 220 of the sleeve 230 can begin in or near
the neck 206 and extend over the shoulder 204. In one example, the
upper portion 220 of the sleeve 230 ends against a bullet 50 (see
FIG. 1B) providing additional material, and thus strength, to help
retain and align the bullet 50. This thickened upper portion 220
can act like an extension of the neck 206 farther down into the
shoulder. The upper portion 220 is an advantage over a brass
cartridge, since brass cannot be formed in this way. Thus, the
upper portion 220 can act to sit and secure the bullet in the same
place in the cartridge every time.
[0057] The sleeve 230, in the illustrated example of FIGS. 3, 4 and
5, extends almost the entire length of the body 202. The sleeve 230
stops at an overlap potion 222 of the upper component 200. The
overlap portion 222 is the portion of the upper component 200 that
engages the lower component 300. The overlap portion 222 has a
thinner wall thickness t, or a second thickness, at the second end
212 than the thickness T of the wall 218 (or T and T+) before the
overlap portion 222. The second thickness t tapers toward the
outside of the upper component 200 so an outer diameter 224 of the
wall 218 remains constant while an inner diameter 226 of the wall
218 increases. This allows certain examples of cartridge 100 to
maintain a constant outer diameter from below the shoulder 204 to
the insert 400. The bottom end 228 of the sleeve 230 is
approximately squared off to provide a square shoulder to keep the
upper 200 and lower 300 components concentric during assembly.
[0058] FIGS. 6-8 illustrate that the lower component 300 has a
tapered portion 306 starting at the lower component first end 302
and ending at a collar 308. The slope of the tapered portion 306
approximately matches the slope of the overlap portion 222 so the
two can slide over each other to engage the upper 200 and lower 300
components. The tapered portion 306 ends in a flat seat 307. The
seat 307 can have a thickness Ts which is about equal to the
thickness of the wall and/or sleeve. This allows the bottom end 228
of the sleeve to sit on the seat 307 when the upper 200 and lower
300 components engage. This prevents the bottom end 228 of the
sleeve 230 from being exposed. This could allow the gases to exert
pressure on the bottom end 228 that can separate the upper 200 from
the lower 300 component.
[0059] A width of the collar 308 matches the second thickness t, so
that the outer diameter of the cartridge 100 remains constant past
the transition point between the upper 200 and lower 300
components. Further, a thickness of the tapered portion 306 is such
that at any point the sum of it with the thickness of the overlap
portion 222 is approximately equal to the thickness T of the wall
218 or the thicknesses of the wall 218 and sleeve 230 (T and T+).
As noted above, the tapered portion 306 and the overlap portion 222
are bonded together to join the upper 200 and lower 300
components.
[0060] An inner wall 310 of the lower component 300 can be formed
straight. In the illustrated example in FIG. 8, the inner wall 310
forms a bowl shape with a hole 312 at the bottom. The hole 312 is
formed as a function of the interface between the lower component
300 and the insert 400, and its formation is discussed below. As
the inner wall 310 slopes inward to form the bowl shape, it forks
and forms an inner bowl 314 and an outer sheath 316. The gap 318
that is formed between the inner bowl 314 and the outer sheath 316
is the space where a portion of the insert 400 engages the lower
component 300. As noted above, in one example, the lower component
300 is molded over a portion of the insert 400 to join the two
parts.
[0061] Turning now to an example of the insert 400, as illustrated
in FIG. 9, it includes an overmolded area 408, where the outer
sheath 316 engages the insert 400 in the gap 318. The overmolded
area 408 has one or more ridges 410. The ridges 410 allow the
polymer from the outer sheath 316, during molding, to forms bands
320 (see, FIG. 8) in the gap 318. The combination of the ridges 410
and bands 320 aid in resisting separation between the insert 400
and the lower component 300. The resistance is most important
during the extraction of the cartridge from the firearm by an
extractor (not illustrated).
[0062] The overmolded area 408 also includes one or more keys 412.
The keys 412 are flat surfaces on the ridges 410. These keys 412
prevent the insert 400 and the lower portion 300 from rotating in
relation to one another, i.e. the insert 400 twisting around in the
lower portion 300.
[0063] Below the overmolded area 408, toward the back end 402, is a
self reinforced area 414. This portion extends to the back end 402
of the insert 400 and includes the extraction groove 404 and rim
406. The self reinforced area 414 must, solely by the strength of
its materials, withstand the forces exerted by the pressures
generated by the gasses when firing the bullet and the forces
generated by the extractor. In the present example, the self
reinforced area 414 withstands these forces because it is made of a
heat treated metal or a metal/non-metal alloy.
[0064] FIGS. 10 and 11 illustrate an example of the inside of the
insert 400. Open along a portion of the back end 402 and continuing
partially toward the overmolded area 408 is a primer pocket 416.
The primer pocket 416 is dimensioned according to the standards for
caliber of the cartridge case and intended use. A primer (not
illustrated) is seated in the primer pocket 416, and, as described
above, when stricken causes an explosive force that ignites the
powder (not illustrated) present in the upper 200 and lower 300
components.
[0065] Forward of the primer pocket 416 is a flash hole 418. Again,
the flash hole 418 is dimensioned according to the standards for
the caliber of the cartridge case and intended use. The flash hole
418 allows the explosive force of the primer, seated in the primer
pocket 418, to communicate with the upper 200 and lower 300
components.
[0066] Forward of the primer pocket 416 and inside the overmolded
area 408 is basin 420. The basin 420 is adjacent to and outside of
the inner bowl 314 of the lower component 300. The basin 420 is
bowl shaped, wherein the walls curve inwards toward the bottom. The
bottom of the basin 420 is interrupted by a ring 422. The ring 422
surrounds the flash hole 418 and extends into the basin 420. It is
the presence of the ring 422 that forms the hole 312 in the inner
bowl 314 of the lower component 300.
[0067] In another example of a cartridge case 120, the sizes of the
upper 200 and lower 300 components can be altered. FIG. 12
illustrates a "small upper" embodiment with a bullet 50 in the
mouth 208 of the cartridge 120. The features of the upper 200 and
lower 300 component are almost identical to the example discussed
above, and the insert 400 can be identical. FIG. 12 also
illustrates the engagement between a lip 214 and the cannelure 55.
The lip 214 is a section of the neck 206 approximate to the mouth
208 that has a thicker cross section or, said differently, a
portion having a smaller inner diameter than the remainder of the
neck 206. In this example, the lip 214 is square or rectangular
shaped, no angles or curves in the longitudinal direction. Note, in
other examples, the upper component 200 is not formed with a lip
214. When present, the lip 214 engages the cannelure 55 formed
along an outer circumferential surface of the bullet 50 when it is
fitted into the mouth 208 of the cartridge casing 100.
[0068] FIG. 13 shows that the neck 206 and the shoulder 204 are
formed similar, but in this example, the body 202 is much shorter.
Further, instead of an overlap portion 222, there is an underskirt
portion 240 that starts very close to the shoulder 204. The
underskirt portion 240 tapers to the inside of the cartridge when
it engages the lower component 300.
[0069] The lower component 300 in this further example, is now much
longer and comprises most of the propellant chamber 340. The
tapered portion is now replaced with an outer tapered portion 342.
The outer tapered portion 342 slides over the underskirt portion
240 so the two can be joined together as noted above. The thickness
of the underskirt portion 240 and the outer tapered portion 342 is
approximate to the wall thickness or wall thickness and sleeve
thickness.
[0070] The inner wall 310 is now substantially longer, can include
a sleeve, but still ends in the inner bowl 314. The engagement
between the second end 304 of the lower component 300 and the
insert 400 remains the same. Note that either the "small upper" or
"long upper" can be used to form blank or subsonic ammunition. The
walls are made thicker with the sleeve, shrinking the size of the
propellant chamber 340. Less powder can be used, but the powder is
packed similarly as tight as it is for a live round because of the
smaller chamber 340. This can prevent the Secondary Explosive
Effect (SEE) (below). A thick wall design for a subsonic cartridge
140 is illustrated in FIG. 14.
[0071] Illustrated is a large upper component 200 having a thicker
overlap 222 portion, with a thickness t+ and an integral thickening
of the wall, and/or a sleeve 230 with a thickness T+, as disclosed
above. The total thickness of the wall 218 can be the sum of T+ and
t+. The sleeve 230 can run the length of the upper component 200
from the mouth 208 to the start of the overlap portion 222. The
lower component 300 of a subsonic cartridge 140 can be thickened as
well. The subsonic cartridge 140 can be made with the insert 400,
or the lower component 300 can be molded in one piece from polymer
with the features of the insert 400. For example, the flash hole
418, primer pocket 416, groove 404 and rim 406. Alternately, the
insert can also be high-strength polymer instead of the metal
alloys discussed above. In this example, the lower component and
the insert can be formed as one piece, and the upper component 200
can be placed on top.
[0072] As illustrated in FIG. 15, for a blank cartridge 150, the
upper component 200 can be made differently. For the blank
cartridge 150, an extension 242 can be molded to extend from the
neck 206. The extension 242 has a star-shaped cap 244 to seal off
the cartridge. The cap 244 is formed partially of radially spaced
fingers 246 that deform outwards during firing. Thus, the mouth 208
is molded partially shut to contain a majority of the pressures and
expand open and outwards. The fingers 246 are designed, in one
example, to be bend elastically and are not frangible. The object
is to contain the majority of the pressures and expel anything that
can act as a projectile out the barrel of the firearm.
[0073] When the blank cartridge 150 is formed with the "small
upper" component 200 with the cap 244. The lower component 300 can
be filled with the powder and the small upper component can act as
a cap to the cartridge, sealing in the powder.
[0074] Note that the above examples illustrate a bottleneck
cartridge. Many of the features above can be used with any
cartridge style, including straight wall cartridges used in
pistols. FIG. 16 illustrates an example of a straight wall
cartridge 500. The straight wall cartridge 500 is a one-piece
design of all polymer. The cartridge 500 has a body 502 and a mouth
508 at a first end 510. The walls 518 of the cartridge casing can
also have a sleeve 530 along a majority of its length.
[0075] The sleeve 230, 530 is dimensioned and shaped pursuant to
the requirements of each cartridge based on blank or subsonic and
the particular caliber. To that end, the sleeve 530 begins set back
from the first end 510 based on the depth the rear of the bullet
sits in the cartridge. Further, in this example, as the walls
transition into a lower bowl 514, the sleeve 530 may extend into
the bowl. This aids in the strength of a back end 512 of the
cartridge 500, since this example lacks a hardened metal
insert.
[0076] The lower bowl 514 curves downward toward a flash hole 517
which then opens to a primer pocket 519. Both are similar to the
features described above. Further, the back end is molded to form a
rim 506.
[0077] Turning now to an example of a fully formed cartridge case
100, FIG. 17 illustrates a cross-section of all three elements
engaged together to illustrate how they interface with each other.
The specific outer dimensions of the three elements and certain
inner dimensions (e.g. mouth 208, lip 214, flash hole 418, and
primer pocket 416) are dictated by the caliber and type of the
firearm and type of ammunition. The cartridge casing 100 of the
present invention is designed to be used for any and all types of
firearms and calibers, including pistols, rifles, manual,
semi-automatic, and automatic firearms.
[0078] An exemplary construction of the upper component 200 also
aids in withstanding the pressures generated. As noted above, the
sleeve 230 increases the strength of the wall 218 of the upper
component 200. In the present example, the upper component 200
accounts for anywhere from 70% to 90% of the length of the
cartridge casing 100.
[0079] The polymer construction of the cartridge case also provides
a feature of reduced friction between the cartridge and chamber of
the firearm. Reduced friction leads to reduced wear on the chamber,
further extending its service life.
[0080] Subsonic ammunition can be manufactured using the above
illustrated examples. Subsonic ammunition is designed to keep the
bullet from breaking the speed of sound (approximately 340 m/s at
sea level or less than 1,100 fps). Breaking the speed of sound
results in the loud "crack" of a sonic boom, thus subsonic
ammunition is much quieter than is standard counterpart. Typical
subsonic ammunition uses less powder, to produce less energy, in
the same cartridge case as standard ammunition. The remaining space
is packed with wadding/filler to keep the powder near the flash
hole so it can be ignited by the primer. As noted above, increasing
the wall thickness eliminates the need for wadding. In one example,
while a brass cartridge wall can be 0.0389'' thick, the polymer
wall and sleeve can have a total thickness of 0.0879'' for the
identical caliber.
[0081] The reduced capacity allows for a more efficient ignition of
the powder and a higher load density with less powder. Low load
density (roughly below 30-40%) is one of the main contributors to
the Secondary Explosive Effect (SEE). SEE can destroy the strongest
rifle action and it can happen on the first shot or the tenth. SEE
is the result of slow or incomplete ignition of small amounts of
smokeless powder. The powder smolders and releases explosive gases
which, when finally ignited, detonate in a high order explosion.
The better sealing effect is also important here because standard
brass does not seal the chamber well at the lower pressures created
during subsonic shooting.
[0082] While the foregoing has described what are considered to be
the best mode and/or other examples, it is understood that various
modifications may be made therein and that the subject matter
disclosed herein may be implemented in various forms and examples,
and that the teachings may be applied in numerous applications,
only some of which have been described herein. It is intended by
the following claims to claim any and all applications,
modifications and variations that fall within the true scope of the
present teachings.
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