U.S. patent application number 10/524427 was filed with the patent office on 2006-03-02 for method of making a frangible non-toxic projectile.
This patent application is currently assigned to Bismuth Cartridge Company. Invention is credited to Robert E. Petersen.
Application Number | 20060042456 10/524427 |
Document ID | / |
Family ID | 31888263 |
Filed Date | 2006-03-02 |
United States Patent
Application |
20060042456 |
Kind Code |
A1 |
Petersen; Robert E. |
March 2, 2006 |
Method of making a frangible non-toxic projectile
Abstract
A method of making a frangible, non-toxic projectile is
described in which substantially pure bismuth metal is melted, a
quantity of the bismuth metal is poured into a mold, the bismuth
metal is cooled to form a substantially bismuth metal core, the
core is swaged in a profile die having a bleed hole of about 0.020
inch to about 0.038 inch in diameter, and the core is
electroplated. The swaging may eliminate substantially a surface
irregularity. The projectile may be releasably disposed in a
cartridge along with a propellant and a primer, in which the primer
ignites the propellant upon contact with a firing pin. The
cartridge may itself be releasably disposed within a barrel of a
firearm.
Inventors: |
Petersen; Robert E.; (Los
Angeles, CA) |
Correspondence
Address: |
ROTHWELL, FIGG, ERNST & MANBECK, P.C.
1425 K STREET, N.W.
SUITE 800
WASHINGTON
DC
20005
US
|
Assignee: |
Bismuth Cartridge Company
7155 Valjean
omitted
|
Family ID: |
31888263 |
Appl. No.: |
10/524427 |
Filed: |
August 13, 2003 |
PCT Filed: |
August 13, 2003 |
PCT NO: |
PCT/US03/25188 |
371 Date: |
August 2, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60403655 |
Aug 16, 2002 |
|
|
|
Current U.S.
Class: |
86/54 |
Current CPC
Class: |
F42B 33/00 20130101;
F42B 30/02 20130101; F42B 12/74 20130101 |
Class at
Publication: |
086/054 |
International
Class: |
F42B 30/02 20060101
F42B030/02 |
Claims
1. A method of making a frangible, non-toxic projectile comprising:
melting substantially pure bismuth metal; pouring a quantity of
said bismuth metal into a mold; cooling said quantity of bismuth
metal to form a substantially crystalline or poly-crystalline
bismuth core; swaging said core in a profile die having a bleed
hole; and electroplating said core so as to form an electroplated
core.
2. The method of making a frangible, non-toxic projectile of claim
1, wherein said bleed hole has a diameter of about 0.020 inch to
about 0.038 inch.
3. The method of making a frangible, non-toxic projectile of claim
1, further comprising cleaning said core after said swaging and
prior to said electroplating.
4. The method of making a frangible, non-toxic projectile of claim
3, further comprising rinsing said core after said cleaning and
prior to said electroplating.
5. The method of making a frangible, non-toxic projectile of claim
1, further comprising: applying a tarnish inhibitor to the
electroplated core; drying the electroplated core; further swaging
the electroplated core; and polishing the electroplated core.
6. The method of making a frangible, non-toxic projectile of claim
1, wherein said swaging eliminates substantially a surface
irregularity.
7. The method of making a frangible, non-toxic projectile of claim
1, wherein said swaging bleeds off from said core about three to
twelve grains of bismuth metal through said bleed hole in said
die.
8. The method of making a frangible, non-toxic projectile of claim
1, wherein said electroplating forms a coating having a thickness
between about 0.005 inch to about 0.008 inch.
9. The method of making a frangible, nontoxic projectile of claim
8, wherein said coating is selected from the group consisting of:
copper, brass, german silver, tin, bronze, and aluminum.
10. The method of making a frangible, non-toxic projectile of claim
1, wherein said electroplating said core comprises further:
immersing said core in an acid activation tank, then immersing said
core in a cyanide strike bath; then immersing said core in an
acid-copper bath; and then applying a voltage across said
acid-copper bath.
11. The method of making a frangible, non-toxic projectile of claim
10, wherein said voltage is applied for a period of between about
seven and about fourteen hours.
12. A frangible, non-toxic projectile comprising: a core of
substantially crystalline or poly-crystalline bismuth; and a
coating electroplatably disposed over said core.
13. The frangible, non-toxic projectile of claim 12, wherein said
coating has a thickness of about 0.005 inch to about 0.008
inch.
14. The frangible, non-toxic projectile of claim 12, wherein said
coating is selected from the group consisting of: copper, brass,
german silver, tin, bronze, and aluminum.
15. The frangible, non-toxic projectile of claim 12, wherein said
projectile is releasably disposed proximate to a first end of a
cartridge, said cartridge comprising further: a propellant disposed
within said cartridge, a primer fixably disposed proximate to a
second end of said cartridge; and wherein said primer ignites said
propellant upon contact with a firing pin.
16. A system for making a frangible, non-toxic projectile
comprising: means for molding substantially pure molten bismuth
metal into a substantially crystalline or poly-crystalline bismuth
core; means operatively associated with the molding means for
swaging said core in a profile die having a bleed hole; and means
operatively associated with the swaging means for electroplating
said core to form an electroplated core.
17. The system for making a frangible, non-toxic projectile of
claim 16, further comprising means operatively associated with and
disposed between the swaging means and the electroplating means for
cleaning said core.
18. The system for making a frangible, non-toxic projectile of
claim 17, further comprising means operatively associated with and
disposed between the cleaning means and the electroplating means
for rinsing said core.
19. The system for making a frangible, non-toxic projectile of
claim 16, further comprising: means operatively associated with the
electroplating means for applying a tarnish inhibitor to the
electroplated core; means operatively associated with the applying
means for drying the electroplated core; means operatively
associated with the drying means for further swaging the
electroplated core; and means operatively associated with the
further swaging means for polishing the electroplated core.
20. The system for making a frangible, non-toxic projectile of
claim 16, wherein said means for electroplating said core to form
an electroplated core comprises further: acid activation tank
immersing means for immersing said core in an acid activation tank,
cyanide strike bath immersing means operatively associated with the
acid activation tank immersing means for immersing said core in a
cyanide strike bath; acid-copper bath immersing means operatively
associated with the cyanide strike bath immersing means for
immersing said core in an acid-copper bath; and means operatively
associated with the acid-copper bath immersing means for applying a
voltage across said acid-copper bath.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Provisional Application
Ser. No. 60/403,655, filed Aug. 16, 2002, the disclosure of which
is incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] This invention relates to the field of projectiles for
firearms and, in particular, to the field of frangible, non-toxic
projectiles for firearms.
[0004] 2. Description of the Related Art
[0005] One measure of the ability of a projectile to penetrate or
stop an object may be its kinetic energy. The higher a projectile's
kinetic energy, the greater the ability of the projectile to
penetrate or stop an object, Kinetic energy (KE) is proportional to
one-half of the product of the mass of a projectile and the square
of its velocity, or KE=1/2mv.sup.2. The kinetic energy of a
projectile may thus be maximized by raising its velocity or its
mass, or both.
[0006] Since kinetic energy is proportional to the square of a
projectile's velocity, velocity may be a logical first parameter
upon which to focus. The velocity of a projectile, however, is
largely a function of the firearm from which it is fired, and is
largely independent of the projectile itself. This leaves the
projectile's mass as the only easily variable parameter.
[0007] The mass of a projectile is a product of the projectile's
volume and the density of the material from which it is made. The
volume of a projectile is limited by the length of the chamber and
the caliber of the firearm, which leaves the projectile's density.
The kinetic energy of a projectile may therefore be maximized by
maximizing its density.
[0008] Lead is often chosen as a material from which to form
projectiles because it is relatively dense. Lead, furthermore, is
soft and deforms easily. The deformability of lead may result in
expansion of the projectile on impact, so-called "mushrooming".
Mushrooming enhances the stopping power of projectiles. Other dense
materials that may be used to make projectiles are tungsten and
depleted uranium. Tungsten is relatively expensive, however, and
both lead and depleted uranium may be toxic.
[0009] Projectiles are often jacketed or coated with an outer layer
of copper or other material to protect the barrel from damage or
fouling. Jacketed projectiles can be made in "soft point" or
"hollow point" configurations to facilitate "mushrooming" of the
projectile and maximizing its stopping power.
[0010] Conventional projectiles often remain in one piece upon
striking a hard surface. Sometimes conventional projectiles
penetrate hard objects or ricochet upon striking a hard surface,
even if they deform. Projectiles that ricochet are undesirable for
use by law enforcement officers because they increase the risk that
innocent by-standers might be injured or killed. Additionally,
ricocheting projectiles or projectiles which penetrate hard objects
are undesirable for use by security personnel at nuclear
facilities, in airplanes, or other sensitive areas, due to the risk
of collateral damage.
[0011] Indoor shooting ranges may have steel backstops. A steel
backstop may be expensive. Projectiles that deform rather than
fragmenting into small pieces may tend to damage a steel backstop.
A steel backstop that has absorbed multiple impacts in the same
area from projectiles that deform rather than fragmenting into
small pieces may eventually require replacement.
SUMMARY OF THE INVENTION
[0012] In a first embodiment, a method of making a frangible,
non-toxic projectile is described in which substantially pure
bismuth metal is melted, a quantity of the bismuth metal is poured
into a mold, the bismuth metal is cooled to form a substantially
crystalline or poly-crystalline bismuth core, the core is swaged in
a profile die having a bleed hole, and the core is electroplated
thereafter. The swaging step may eliminate substantially a surface
irregularity. In one embodiment, the bleed hole may have a diameter
of about 0.020 inch to about 0.038 inch in diameter.
[0013] In a second embodiment, a projectile is formed of a core of
substantially crystalline or poly-crystalline bismuth electroplated
with copper or an alloy of copper.
[0014] In a third embodiment, the projectile may be releasably
disposed in a cartridge along with a propellant and a primer, in
which the primer ignites the propellant upon contact with a firing
pin. The cartridge may itself be releasably disposed within a
barrel of a firearm.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] FIGS. 1A through 1N show some steps of a process for making
a frangible, non-toxic projectile according to a first embodiment
of the invention;
[0016] FIG. 2 shows a projectile for a firearm according to an
embodiment of the invention;
[0017] FIG. 3 shows a cartridge for a firearm according to an
embodiment of the invention;
[0018] FIG. 4 shows a firearm for use with an embodiment of the
invention;
[0019] FIG. 5 shows an unbled core for use with an embodiment of
the invention;
[0020] FIGS. 6A and 6B show a core being bled according to a second
embodiment of the invention; and
[0021] FIG. 7A shows a projectile shattering according to an
embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Since projectiles are expendable, it would be desirable for
a projectile to be made of a relatively inexpensive material.
[0023] Since there may be a risk of environmental damage associated
with a projectile that is made of a toxic material, it would be
desirable for a projectile to be made of a relatively inexpensive,
non-toxic material.
[0024] Since the kinetic energy of a projectile may be maximized
for a projectile that is made of a dense material, it would be
desirable for a projectile to be made of a relatively inexpensive,
non-toxic, and dense material.
[0025] Since there may be a risk of collateral damage associated
with a projectile that ricochets, it would be desirable for a
projectile to be made of a relatively inexpensive, non-toxic, dense
and frangible material. A frangible projectile may break up upon
impact with a hard surface, thus reducing or eliminating the risk
that the projectile will ricochet off a hard surface or penetrate
too deeply.
[0026] Since it would be desirable for a projectile to be made of a
relatively inexpensive, non-toxic, dense and frangible material, it
would be desirable for a projectile to be made of substantially
pure bismuth. It would further be desirable for a substantially
pure bismuth core to contain no more than trace amounts of
naturally-occurring elements, which may be toxic. If would further
be desirable for a substantially pure bismuth core to contain less
than about 100 ppm of impurities, which also may be toxic. It would
further be desirable for a substantially pure bismuth core to
contain essentially no naturally-occurring trace elements besides
bismuth.
[0027] Molten bismuth may be poured in a mold to form a projectile
or a projectile core. Molten bismuth, however, may tend to be
relatively liquid and water-like, and of a thin consistency. When
molten bismuth is poured into a mold, the molten bismuth may have a
tendency to splash. Molten bismuth may trap air between the molten
bismuth and a surface of the mold if it splashes.
[0028] Trapped air may produce one or more creases or folds in the
solidified core. A fold may produce a noticeable defect in the
surface of the plating, requiring that the projectile be scrapped.
Furthermore, a fold that occurs near the heel of a projectile may
degrade projectile accuracy. Finally, moisture may be trapped in a
fold.
[0029] Trapped moisture may be converted to steam while the core is
being electroplated or heat-dried. The steam may escape, rupturing
the plating. The steam may also weaken the electrolytic bond
between the core and the plating. The steam may cause discoloration
of the plating. It would be desirable if the size or the incidence
of folds or creases could be reduced or eliminated before a core is
electroplated.
[0030] A core may be swaged in a profile or bleed die to size a
core before electroplating. If the pressure required to swage the
core is high enough, it may close folds left on the surface of the
core.
[0031] A bleed hole may be located in the side of the bleed die.
Some of the bismuth may bleed off, i.e. extrude out through the
bleed hole while a core is being swaged, thus reducing the size and
weight of the core. Since a portion of the bismuth core may be
extruded through the bleed hole during the swaging process, the
pressure required to swage or fully form the core may be related to
the force required to extrude bismuth through the bleed hole. In
particular, the pressure required to swage the core may be related
to the smallest diameter, the smallest area, or the surface
resistance of the bleed hole.
[0032] A profile die may be made of a relatively hard material such
as tungsten-carbide. A bleed hole of a small diameter may be
difficult to drill in a hard material. A standard size bleed hole
of the type used in the industry to bleed a lead or lead-antimony
bullet core may have a diameter of about 0.050 inch to about 0.062
inch. A bleed hole of this diameter however, may not allow much
in-die pressure to develop, especially when attempting to bleed
core materials that are harder than lead or lead alloy. If bismuth
is being extruded it may extrude too easily for a significant
amount of in-die pressure to develop. In particular, the pressure
may be insufficient to cause the folds to close up completely. In
effect, the core may be bled to weight before the bismuth lying
near the exterior surface can be rearranged materially.
[0033] It would therefore be desirable if a core could be bled more
slowly, allowing higher pressures to develop and giving the folds
near the surface of the core time to close. It would further be
desirable if a bleed hole of smaller diameter could be formed in
the profile die to offer more resistance to the extruded bismuth,
allowing higher pressures to develop and slowing the bleeding
process down to give the folds near the surface of the core time to
close.
[0034] A bismuth core may be inserted into a metal jacket. A jacket
may be made of copper or a copper alloy, such as an alloy of 95%
copper and 5% zinc. A copper alloy jacket, however, may tend to
flatten rather than breaking up on impact. Such a jacket may be too
thick or tough to fragment into small pieces. Furthermore, since
copper and its alloys may be malleable, it may protect the bismuth
core from breaking up as well. It would be desirable for a copper
or copper alloy jacket to break up on impact, along with the
bismuth core.
[0035] Furthermore, electroplating may have certain advantages over
a conventional projectile jacket when combined with pure bismuth,
such as an ability to fill in the flats and angles on the surface
of crystalline or poly-crystalline bismuth. This may make a
projectile produced by pouring a pure bismuth core and
electroplating it more balanced, and therefore more accurate, than
a projectile made by inserting bismuth into a jacket. It would be
desirable for a coating to be electroplated on a bismuth core.
[0036] Furthermore, the chemical bond formed between the cladding
and the bismuth core by electroplating may produce a more frangible
projectile than a conventional jacketed projectile, since a
conventional projectile jacket may have a propensity to flatten on
impact instead of breaking apart. A flattening jacket may thus
impede fragmentation of the core. A chemical bond between an
electroplated coating and a bismuth core, on the other hand, may be
strong enough to break the coating up into small pieces at the same
time the core breaks up when the projectile strikes an object, such
as a steel backstop. It would thus be desirable for a coating to be
electroplated on a bismuth core.
[0037] In FIG. 1 is shown a process for making a frangible,
non-toxic projectile according to a first embodiment of the
invention. As shown in FIG. 1A, substantially pure bismuth metal
may be heated to a temperature above its melting temperature
(271.3.degree. C., 520.3.degree. F.) until it melts. As shown in
FIG. 1B, a quantity of the molten bismuth may be poured into a mold
122, which may have a cavity 124 of generally ogival shape. In
alternative embodiments, cavity 124 may have a spherical, oblong,
ovoid, cylindrical, conical, frustoconical or ellipsoid shape. In
one embodiment, a fold 152 may form in a surface of core 118, as
shown in FIG. 5.
[0038] As the quantity of bismuth cools it solidifies to form a
core 118, as shown in FIG. 1C. If mold 122 is not disturbed unduly,
while the bismuth cools, a single crystal of bismuth may be formed.
In the alternative, polycrystalline bismuth may be formed.
[0039] As shown in FIG. 1D, the solidified; bismuth core 118 may be
inserted in a profile die 126 which may also have a profile of
generally ogival shape. Profile die 126 may have a bleed hole 128.
There may be more than one bleed hole 128. Bismuth core 118 may be
swaged in profile die 126 using pressure sufficient to force
bismuth core 118 to assume the shape of profile die 126. Some of
the bismuth may bleed off while bismuth core 118 is being swaged.
In one embodiment, about three to about twelve grains of bismuth
metal may be bled off. The bismuth extruded through bleed hole 128
may form a bleed wire 129. Bleed wire 129 may be removed from core
118. In one embodiment, bleed wire 129 is removed by shearing it
off core 118.
[0040] In one embodiment, bleed hole 128 may be formed in profile
die 126 with an electronic discharge machine (EDM). An EDM may form
a bleed hole 128 of 0.020 inch diameter. A bleed hole 128 of about
0.020 inch diameter internal may increase the die pressure
developed during swaging and close or eliminate fold 152 in the
surface of the bismuth core. In alternative embodiments, a diameter
of the bleed hole may vary between about 0.020 inch and about 0.032
inch. In one embodiment, the diameter of the bleed hole depends on
the size of the core. In one embodiment, bismuth core 118 may be
rearranged sufficiently during the swaging process to close fold
152.
[0041] As shown in FIGS. 1E and 1F, bismuth core 118 may be
prepared for electroplating by cleaning it in a detergent bath 144
to remove contaminants and surface residue. A clean surface may be
important for effective electroplating. Detergent residue left from
the cleaning process may then be rinsed off.
[0042] As shown in FIGS. 1G through 1J, bismuth core 118 may then
be placed in an acid activation tank 146, rinsed, and immersed in a
cyanide strike bath 148. Bismuth core 118 may then be rinsed
further and immersed in an acid-copper bath 132. Bismuth core 118
may be connected to a cathode 134 of a voltage source, and a
voltage may be applied across the acid-copper bath 132 by immersing
a corresponding anode 136 in the bath 132 for a period of between
about seven and about fourteen hours.
[0043] The electroplating process may proceed until bismuth core
118 is substantially completely covered with a coating 120 of
copper, forming a projectile 114. In alternative embodiments,
bismuth core 118 may be substantially completely covered with a
coating 120 of brass, german silver, tin, bronze, or aluminum. The
cathode 134 and the anode 136 may be reversed in the case of some
coatings 120, depending on the electrical potential of the coating
120 relative to that of the bismuth. In an alternative embodiment,
such as in the case of an aluminum coating, core 118 may be
anodized.
[0044] Coating 120 may have a thickness between about 0.005 inch
and about 0.008 inch per side. As shown in FIGS. 1K and 1L, a
tarnish inhibitor 154 may be applied to the projectile 114, after
which it may be dried in a dryer 156.
[0045] As shown in FIGS. 1M and 1N, projectile 114 may be swaged in
a second profile die 138 to force it to assume a desired final
shape and size, after which it may be tumble-polished in a barrel
150 containing polishing media 151. Projectile 114 may then be
inspected and packaged.
[0046] In FIG. 6A is shown a core 218 being bled in a profile die
226 according to a second embodiment of the invention. Profile die
226 has a bleed hole 228 through which a bleed wire 229 may be
extruded. In FIG. 6B a knockout punch 230 is shown ejecting core
218 after it has been bled.
[0047] In FIG. 2 is shown a projectile 114 for a firearm according
to a second embodiment of the invention. A core 118 of projectile
114 may be formed of substantially pure crystalline or
poly-crystalline bismuth. In one embodiment, core 118 of projectile
114 may be brittle or frangible and break apart or shatter upon
impacting a hard or rigid surface. When core 118 shatters, as shown
in FIG. 7, its kinetic energy may be distributed among individual
particles 121. Individual particles 121 may possess low individual
energies. A tendency of individual particles 121 to ricochet may
consequently be reduced. An ability of individual particles 121 to
penetrate objects with unintended consequences may also be
reduced.
[0048] In a preferred embodiment, core 118 may be gravity cast. If
core 118 is gravity cast, molten bismuth may be poured into a mold
that may have the same basic shape or profile as the final
projectile. In alternative embodiments, core 118 may be sand cast,
permanent mold cast, die cast, investment cast, or cast by a lost
wax or lost foam process.
[0049] Core 118 may be electroplated with a coating 120 such as
copper, a copper alloy such as brass, bronze, german silver, or
aluminum. In a preferred embodiment, coating 120 may be about 0.007
inch thick.
[0050] In one embodiment, core 118 may be slightly longer than
projectile 114. Core 118 may be slightly longer than projectile 114
because it is still in "unbled" condition as it comes out of the
mold. Bleeding the core to final weight may decrease the length so
that it is several thousandths of an inch shorter than projectile
114.
[0051] In one embodiment, core 118 may be approximately 0.014 inch
shorter than projectile 114. In one embodiment, core 118 may be
slightly narrower than projectile 114. Core 118 may be slightly
narrower than projectile 114 because it lacks the thickness
provided by coating 120.
[0052] In FIG. 3 is shown a cartridge 100 for a firearm according
to a third embodiment of the invention. Cartridge 100 may include a
casing 102 which may be made of an alloy of copper, such as brass.
An explosive propellant 104 in the form of a powder may be
contained within casing 102. Casing 102 may further have a primer
108 at a rear end 110 to ignite propellant 104. Primer 108 may be
actuated by a firing pin 112 of the firearm. Projectile 114 may be
held within neck 116 of casing 102, a core of which may be formed
of substantially pure crystalline or poly-crystalline bismuth.
Projectile 114 may be expelled from casing 102 by propellant
104.
[0053] In FIG. 4 is shown a firearm 140 for use with an embodiment
of the invention. Cartridge 100 may be insertably disposed within a
barrel 142 of firearm 140. Projectile 114 may be used in a pistol
or a rifle of .22 caliber to .50 caliber, as a slug in a shotgun of
10, 12, 16, or 20 gauge, or .410 caliber, or in a cannon of up to
about 16 inch diameter.
[0054] While the invention has been described in detail above, the
invention is not intended to be limited to the specific embodiments
as described. It is evident that those skilled in the art may now
make numerous uses and modifications of and departures from the
specific embodiments described herein without departing from the
inventive concepts.
* * * * *