Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
Improved Reduced Energy Cartridge and Method of Making Same
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not Applicable
FIELD OF THE INVENTION
[0001] The invention relates to cartridges for firearms that are designed for,
or are
temporarily or permanently modified to be used in, reality-based training
exercises. In
particular, the invention relates to a two-piece reduced energy cartridge.
BACKGROUND OF THE INVENTION
[0002] Reduced energy cartridges for use in training or practice exercises are
well
known. Regardless of what application it is used in, an important
characteristic of a
firearm cartridge is its ability to cycle the slide on firearm. The forward
momentum of a
projectile creates recoil, or backward momentum, in the firearm. If the recoil
is
sufficient, the firearm is cycled. Projectiles of higher mass create more
recoil than
projectiles of lower mass, a result of the conservation of momentum. Training
cartridges
necessarily use low mass projectiles, and as a result, cycling is a problem.
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[0003] One design used to solve the cycling problem in training cartridges is
that
of telescopically interfitted two-piece cartridges. After the explosive
material is ignited
in such a two-piece cartridge, the low-mass projectile, located in a first
part of the
cartridge, is expelled from the firearm by a portion of the gas created upon
ignition. The
remaining gas created during ignition of the explosive material is used to
drive a second
part of the cartridge rearwardly to cycle the firearm.
[0004] One objective in designing such a training cartridge is the
minimization
of cost. Another objective is minimization of explosive material in the
cartridge. The
quantity of explosive material must be sufficient to cycle the firearm, but
also low
enough to prevent the projectile from leaving the firearm at an unsafe
velocity.
[0005] Information relevant to attempts to address these problems can be found
in the following U.S. Patents and U.S. Patent Application Publications:
5,035,183;
5,359,937; 6,439,123; 6,575,098; and 2005/0183612. However, each one of these
single-primer references suffers from one or more of the following
disadvantages: the
use of excessively large quantities of explosive material that damages the
bolt-face of the
firearm; complex component design; and/or complex component assembly.
[0006] The art referred to and/or described above is not intended to
constitute an
admission that any patent, publication or other information referred to herein
is "prior
art" with respect to this invention. In addition, this section should not be
construed to
mean that a search has been made or that no other pertinent information
exists.
[0007]
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[0008] Without limiting the scope of the invention a brief summary of some of
the claimed embodiments of the invention is set forth below. Additional
details of the
summarized embodiments of the invention and/or additional embodiments of the
invention may be found in the Detailed Description of the Invention below.
[0009] A brief abstract of the technical disclosure in the specification is
provided
as well.
SUMMARY OF THE INVENTION
[0010] At least one embodiment of the present invention is directed toward a
method of manufacturing a cartridge for use in a firearm. The method comprises
providing a cartridge body wherein a first portion of the cartridge body
defines a forward
cavity and a second portion of the cartridge body defines a rearward cavity.
An aperture
interconnects the forward and rearward cavities. The cartridge body is
configured to be
disposed about at least a portion of a piston. The method further comprises
providing a
piston wherein the piston has a top end and a bottom end. A portion of the
bottom end
defines a primer retaining cavity. A portion of the piston defines a gas
passageway
extending from the primer retaining cavity to the top end of the piston. The
method
further comprises inserting a primer into the primer retaining cavity of the
piston and
securing the primer in the primer retaining cavity. The method further
comprises placing
a seal member around the piston, inserting the piston and seal member
combination into
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the rearward cavity of the cartridge body, and crimping at least a portion of
the second
portion of the cartridge body to the piston.
[0011] At least one embodiment of the present invention is directed towards a
cartridge for firearms. The cartridge includes a piston, a cartridge body, a
primer, and a
seal member. The piston has a top end and a bottom end. A portion of the
bottom end of
the piston defines a primer retaining cavity. And, a portion of the piston
defines a gas
passageway which extends from the primer retaining cavity to the top end of
the piston.
A first portion of the cartridge body defines a forward cavity and a second
portion of the
cartridge body defines a rearward cavity. An aperture interconnects the
forward and
rearward cavities. The cartridge body is configured to be disposed about at
least a
portion of the piston. At least a portion of the second portion of the
cartridge body is
crimped about the piston. A seal member is arranged around the piston, forming
a seal
between the piston and an inner surface of the rearward cavity of the
cartridge body. The
piston has two positions: an unfired position and a fired position. In the
unfired position
the top end of the piston is adjacent the aperture. In the fired position the
piston has
sealingly slid rearward in the rearward cavity. A primer is arranged in the
primer
retaining cavity of the piston whereby upon firing, the gas created by the
primer flows
through the gas passageway. A portion of the gas flows through the aperture,
and a
portion of the gas fills the rearward cavity between the seal and the
aperture, which
causes the piston to sealingly slide rearward.
[0012] These and other embodiments which characterize the invention are
pointed out with particularity in the claims annexed hereto and forming a part
hereof.
However, for further understanding of the invention, its advantages and
objectives
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obtained by its use, reference should be made to the drawings which form a
further part
hereof and the accompanying descriptive matter, in which there is illustrated
and
described embodiments of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
[0013] A detailed description of the invention is hereafter described with
specific
reference being made to the drawings.
[0014] FIG. 1 is an exploded view of an embodiment of the present invention
depicting the components of a cartridge.
[0015] FIG. 2 is cross-sectional view of an embodiment of the present
invention
depicting a cartridge in an unfired position.
[0016] FIG. 3 is a cross-sectional view of an embodiment of the present
invention
depicting a cartridge in a fired position.
[0017] FIG. 4 is a perspective cross-sectional view of an embodiment of the
present invention depicting a cartridge body with a vent hole.
[0018] FIG. 5 is a perspective cross-sectional view of an embodiment of the
present invention depicting a cartridge with a rupture disc.
[0019] FIG. 6 is a perspective cross-sectional view of an embodiment of the
present invention depicting a cartridge with a rupture disc.
[0020] FIG. 7 is a perspective cross-sectional view of an embodiment of the
present invention depicting a cartridge with a seal member integral to the
piston.
[0021] FIG. 8 is a flowchart of an embodiment of the present invention
depicting
a method of making a cartridge.
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DETAILED DESCRIPTION OF THE INVENTION
[0022] While this invention may be embodied in many different forms, there are
described in detail herein specific preferred embodiments of the invention.
This
description is an exemplification of the principles of the invention and is
not intended to
limit the invention to the particular embodiments illustrated.
[0023] For the purposes of this disclosure, like reference numerals in the
figures
shall refer to like features unless otherwise indicated.
[0024] Embodiments of the present invention make use of telescopically
interfitted two-part cartridges. The components are designed such that they
can be easily
produced and assembled at a lower cost than other designs.
[0025] At least one embodiment of the present invention is directed toward a
firearm cartridge. Examples of the components to be assembled into a cartridge
10 are
depicted in FIG. 1. The telescopically interfitted cartridge 10 of FIG. 1 is
comprised of a
cartridge body 20, a piston 25, a seal member 30, and a primer 35.
[0026] Referring to FIGs. 2 and 3, the cartridge body 20 has five primary
design
features: a forward cavity 40 that retains a projectile; a rearward cavity 45
(as best seen
in FIG. 3) into which the piston 25 is inserted; a divider 50 which separates
the forward
and rearward cavities; an aperture 55 within the divider 50 interconnecting
the forward
and rearward cavities, the aperture 55 acting to limit the gas flow to a
projectile thereby
limiting the projectile's velocity; and a top chamfer 60 which aids in feeding
cartridges
into the magazine and the firearm. It should be noted that the top chamfer 60
is not
required in all embodiments of the invention.
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[0027] As mentioned above, the cartridge 10 also comprises a piston 25 wherein
the piston has a top end 65 and a bottom end 70. A portion of the bottom end
70 defines
a primer retaining cavity 75 for retaining the primer, as best seen in FIGs. 2
and 3. A
portion of the piston defines a gas passageway 80 extending from the primer
retaining
cavity 75 to the top end 65 of the piston.
[0028] Still referring to FIGs. 2 and 3, the cartridge body 20 is configured
to be
disposed about at least a portion of the piston 25, thus forming a
telescopically interfitted
two-part cartridge 10. The inner diameter 85 of the cartridge body 20 and the
outer
diameter 90 of the piston 25 are configured to allow the piston body 25 to be
inserted into
the cartridge body 20.
[0029] The function of the piston before firing is to hold the seal member 30
and
primer 35 in place. Referring now to FIG. 2, which depicts the cartridge 10 in
an unfired
state, the top end 65 of the piston is adjacent the divider 50. The piston 25
is almost
completely contained within the rearward cavity 45 of the cartridge body 20.
Furthermore, a portion 92 of the cartridge body is crimped to the piston 25.
As best seen
in FIG. 3, which depicts the cartridge 10 in a fired state, crimped portion 92
impacts
protrusion 93 after firing. Because the inner diameter of the crimped portion
92 is less
than the outer diameter of the protrusion 94, the piston and cartridge body do
not
physically separate after firing.. Instead, after firing the piston slides
rearwardly,
remaining slidingly engaged to the cartridge body in a telescopic manner.
[0030] The seal member 30 provides a seal between the piston 25 and cartridge
body 20 so that the entire travel of the piston, from an unfired position to a
fired position,
is sealed. Gases created upon firing escape only through the aperture 55. More
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specifically, upon initiation of the primer, gas travels through the gas
passageway 80 and
reaches the divider 50. The gas fills the portion of the rearward cavity
between the
cartridge body 20, the piston 25, and the seal member 30. The seal member 30
prevents
the gas from escaping rearwardly.
[0031] In a primer-only embodiment, the term "primer" as used herein includes
any detonating gas generator. In some embodiments, the present invention
utilizes a gas
generating primer that relies on heat to increase internal pressure: Gas is
generated then
heated. This creates an expansion of less gas to more volume than cooler
systems.
Information related to such a gas generating primer can be found in the
pending U.S.
Patent Application entitled "NON-TOXIC PERCUSSION PRIMERS AND METHODS
OF PREPARING THE SAME", Attorney Docket No. A39.2B-13252-USOI, the entire
contents of which are incorporated herein by reference.
[0032] In some embodiments, the cartridge body 20 further includes a vent hole
96, as depicted in FIG. 4, in order to allow gases to escape and further
reduce the energy
available to the projectile. The vent hole 96 is desirably placed forward the
top end 65 of
the piston when the piston is in the fired position. A person of skill in the
art will
recognize that the size of the vent hole will vary, depending on the
primer/propellant
system used. However, in some embodiments the size of the vent hole is
approximately
0.050 inches.
[0033] At least one embodiment of the present invention employs the use of a
rupture disc 98 to regulate internal pressures, as shown in FIGs. 5 and 6. In
FIG. 5 the
rupture disc 98 is placed within the rearward cavity 45 and adjacent the
aperture 55.
Figure 6 depicts another embodiment of a rupture disc 98, with the disc 98
placed within
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the gas passageway 80. In some embodiments, the rupture disc 98 has a
thickness of
approximately 0.010 inches.
[0034] In at least one embodiment, the seal member 30 is an O-ring, as
depicted
in FIGs. 1- 3. However, one skilled in the art will recognize that a number of
other seal
members may be used to accomplish the sealing effect created by the O-ring.
[0035] In another embodiment, the seal member is integral to the piston 25, as
shown in FIG. 7. As seen in FIG. 7, the design of the piston 25 has eliminated
the need
for a separate seal member.
[0036] In some embodiments of the present invention, a propellant 94 is
further
included in the piston 25, as shown in FIG. 2. One of skill in the art will
recognize that
there are a variety of materials that can be used as a propellant, such as
single or double
based propellants. In at least one embodiment, the propellant 94 is placed
within the gas
passageway 80 of the piston.
[0037] As mentioned above, in some embodiments, the cartridge 10 is also
manufactured with a projectile 95. In at least one embodiment, the projectile
95 is
comprised of a cup 100, a marking material 105, and a cap 110, as depicted in
FIG. 1. In
one embodiment, the projectile 95 is inserted into the forward cavity 40 of
the cartridge
body 20. After firing, as gas escapes from the rearward cavity 45 to the
forward cavity
40 through the aperture 55, the projectile 95 is forced from the forward
cavity and out the
barrel of the firearm.
[0038] It should be noted that in other embodiments, the projectile 95 is
comprised of a rubber bullet, a blank, or oleoresin capsicum spray. One of
ordinary skill
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should recognize that there are a number of other projectiles that can be
substituted for
any of the above examples.
[0039] At least one embodiment of the present invention is directed toward a
method of manufacturing the cartridge described above, as depicted in the
flowchart in
FIG. 8. The method comprises the step 200 of providing a cartridge body 20 and
a piston
25, as described above.
[0040] The method further comprises the step 210 of priming the piston 25.
This
step involves inserting a primer 35 into the primer retaining cavity 75 of the
piston.
[0041] After the primer 35 has been inserted into the piston 25, the method
further comprises the step 215 of securing the primer in the primer retaining
cavity 75.
One of skill in the art will recognize that there are a number of ways the
primer may be
secured within the primer retaining cavity. In one embodiment, securing the
primer to
the piston involves staking the piston. One method of staking the piston may
entail using
a machine to push inwardly portions of the piston material surrounding the
primer. Once
sufficient material has been pushed inwardly, the primer will be securingly
retained
within the primer retaining cavity.
[0042] After the primer is staked, the method further comprises the step 225
of
placing a seal member 30 around the piston.
[0043] Next, the-method further comprises the step 230 of inserting the piston
and
seal member combination into the rearward cavity 45 of the cartridge body 20.
As stated
above, the inner diameter 85 of the cartridge body 20 and the outer diameter
90 of the
piston 25 are configured to allow the piston 25 to be inserted into the
cartridge body 20.
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[0044] Still referring to FIG. 8, the method further comprises the step 235 of
crimping at least a portion 92 of the cartridge body 20 to the piston 25. In
one
embodiment, the crimped portion 92 is located as close to the bottom end 70 of
the piston
as possible, thus allowing the greatest amount of travel.
[0045] In some embodiments, the step 235 of crimping is performed by two
partially annular jaws. The cartridge is placed within jaws and as they are
brought
together by a predetermined force, through a predetermined distance, or some
other
measurement used by those skilled in the art, a portion of the cartridge body
is
compressed onto the piston.
[0046] In at least one embodiment, the step 235 of crimping comprises crimping
the bottom portion of the cartridge body so that the inner diameter 85 of the
rearward
cavity in the crimped portion is less than the inner diameter 85 of the rest
of the rearward
cavity 45, as seen in FIG. 2.
[0047] As a non-limiting example, some embodiments of cartridge bodies before
crimping have an outer diameter of approximately 0.359 inches and after
crimping have
an outer diameter of approximately 0.350 inches. These dimensions will vary
with other
embodiments because the size of the firearm may dictate larger or small
cartridges,
however this ratio as proved to be sufficient to secure the cartridge body and
the piston.
[0048] In at least one embodiment, the method further includes the step 240 of
inserting a projectile 95. The step of inserting a projectile may comprise
inserting a cup
100 into the forward cavity 40 of the cartridge body. Then, a marking material
105, such
as ink or some other agent for marking known by those skilled in the art, is
distributed
into the cup 100. Although amounts may vary depending on the size of the
cartridge and
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the amount of marking material desired, an amount of material in some
embodiments is
1.5 grains. A cap 110 is then inserted into the cup 100 and marking material
combination.
[0049] The step 240 of inserting the projectile 95 can be performed at various
stages of manufacture. In some embodiments, the step of inserting the
projectile is
performed prior to the step 230 of inserting the piston and seal member
combination into
the cartridge body. In such an embodiment, it may be desirable to further
include a step
245 of inverting the cartridge body and projectile combination prior to the
step 230 of
insertion of the piston and seal member combination. Also, it may be desirable
in such
an embodiment to further include a vent 125 in cup 100, as depicted in FIG. 1.
The vent
125 may prevent the projectile from becoming dislodged from the forward cavity
40
during the step of piston insertion into the cartridge body.
[0050] In at least one embodiment, the method also comprises the step 250 of
inspecting the piston for damage. In one embodiment, the inspection step 250
is
performed immediately after the step 215 of securing the primer in the primer
retaining
cavity. The inspection step 250 ensures that the primer has not been damaged
during
securement. Additionally, the inspection step 250 ensures that the primer has
been fully
secured to the piston.
[0051] In some. embodiments, a first machine performs the steps of primer
insertion, primer securement, and piston inspection. A second machine performs
the
steps of placing the seal member, inserting the piston and seal member
combination into
the cartridge body, and crimping the cartridge body.
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[0052] In some embodiments, after the primer and piston combination leaves the
first machine, it may be placed into a feeder bowl of the second machine. The
second
machine may stretch a seal member, drawn from another feeder bowl, and place
it over a
piston. Also, the second machine may draw a cartridge body from a feeder bowl,
draw a
cup from another feeder bowl, and insert the cup into the forward cavity of
the previously
drawn cartridge body. A marking material is then distributed into the cup by
the second
machine, and a cap is drawn from a feeder bowl and inserted into the cup and
marking
material combination.
[0053] In at least one embodiment, the second machine then inverts the
cartridge
and projectile combination. At this point, the second machine may then insert
the piston
into the cartridge body and the second machine crimps the cartridge body to
the piston,
after which the cartridge is placed in a tray as a finished unit.
[0054] The above description should make clear the advantages of the present
inventive methods of manufacturing a cartridge. The components, in particular
the
cartridge body and the piston, are designed such that they can be easily
produced and
assembled. At least one embodiment of the present invention eliminates
complicated
piston and cartridge body alignment *requirements. Furthermore, at least one
embodiment
of the present invention uses less primer than that required by other designs,
thereby
reducing or eliminating damage to the gun's bolt face while still having
enough energy to
cycle the firearm.
[0055] The above disclosure is intended to be illustrative and not exhaustive.
This description will suggest many variations and alternatives to one of
ordinary skill in
this art. The various elements shown in the individual figures and described
above may
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be combined or modified for combination as desired. All these alternatives and
variations are intended to be included within the scope of the claims where
the term
"comprising" means "including, but not limited to".
[0056] Further, the particular features presented in the dependent claims can
be
combined with each other in other manners within the scope of the invention
such that
the invention should be recognized as also specifically directed to other
embodiments
having any other possible combination of the features of the dependent claims.
For
instance, for purposes of claim publication, any dependent claim which follows
should be
taken as alternatively written in a multiple dependent form from all prior
claims which
possess all antecedents referenced in such dependent claim if such multiple
dependent
format is an accepted format within the jurisdiction (e.g. each claim
depending directly
from claim 1 should be alternatively taken as depending from all previous
claims). In
jurisdictions where multiple dependent claim formats are restricted, the
following
dependent claims should each be also taken as alternatively written in each
singly
dependent claim format which creates a dependency from a prior antecedent-
possessing
claim other than the specific claim listed in such dependent claim below.
[0057] This completes the description of the embodiments of the invention.
Those skilled in the art may recognize other equivalents to the specific
embodiment
described herein which equivalents are intended to be encompassed by the
claims
attached hereto.
