The present invention relates to lead-free projectiles, especially bullets, and in particular to lead-free projectiles of increased density (grain). The present invention also relates to methods of manufacture of such projectiles.
Firearms are used in a variety of ways, including hunting and sporting activities, law enforcement activities and military activities. In hunting activities, spent bullets or parts of spent bullets remain in the environment. They may be eaten by game, or other animals or birds, either inadvertently or out of curiosity. This can cause poisoning effects, depending on the type of bullet. If the bullets contain lead, poisoning and environmental effects pose significant concerns about health issues, and have resulted in governmental regulations concerning the banning of the use of lead in bullets. In sporting activities and testing of bullets at a firing range, fumes from lead bullets pose a significant health issue.
Lead-free bullets are known. For instance, U.S. Pat. No. 5,399,187 discloses a bullet formed from tungsten, or an alloy of tungsten, and phenol formaldehyde or polymethylmethacrylate polymers, U.S. Pat. No. 5,012,743 discloses a light weight elongated projectile formed from a casing of copper alloy, steel or similar material and a lower density core e.g. polycarbonate or polyamide. WO 95/23952 discloses a projectile having a core of polyethylene and iron. Projectiles formed from bismuth alloys are disclosed in WO 92/08097 and WO 95/08748.
Lead-free bullets that are particularly intended to retain markings of the barrel of the firearm after the bullet is fired are disclosed in U.S. patent application Ser. No. 09/101,844, filed Oct. 5, 1998 of A. J. Cesaroni. Such bullets have a core formed from a lead-free composition of a filler and an amorphous or low crystallinity polymer e.g. ethylene/methacrylic acid copolymer ionomers, polyetherester elastomers and polyamides. Examples of the filler include copper, tungsten, bismuth, tin and stainless steel. In embodiments, the shell or casing of the bullet may be a truncated cone or truncated parabellum, and the tip may be parabolic, rounded or hollow point.
Lead-free projectiles that are currently being manufactured have, for 0.223 calibre, a maximum weight of about 50 grains. Higher weights for the same calibre would have greater impact during use.
Examples of lead-free projectiles are being manufactured from powdered metals using a sintering process. However, such projectiles do not give the desired results when penetrating tissue. The projectile tends to remain intact and consequently induces minimal trauma when penetrating tissue. Moreover, the projectile will ricochet if it hits a hard object, scattering projectile materials and potentially injuring innocent persons, including the shooter. In addition, the manufacturing process typically includes a step of crimping the projectile into a brass casing, and that step may lead to fracture of the projectile.
A lead-free projectile that could be manufactured with a higher weight, and a manufacturing process that is not susceptible to the above defects of manufacture would be useful.
One aspect of the present invention provides a lead-free projectile having a metal jacket with a tip in the form of a truncated parabellum, said metal jacket being partially filled with cold-pressed metal powder, the remainder of the metal jacket being filled with metal-filled polymer, said metal-filled polymer extending through the truncated parabellum and forming a tip on said projectile.
In preferred embodiments of the invention, the projectile is a bullet.
In further embodiments, the jacket is a copper jacket.
In still further embodiments, the metal powder is copper or tungsten.
In another embodiment, the metal-filled polymer is an amorphous or low crystallinity polymer, especially ethylene/methacrylic acid copolymer ionomer, polyetherester elastomer or polyamide, filled with particles of copper, tungsten, bismuth, tin and/or stainless steel.
Another aspect of the present invention provides a method of forming a lead-free projectile, comprising:
(a) placing a pre-formed open ended metal jacket in a mould, said jacket being formable under pressure;
(b) adding a pre-determined amount of metal powder into said jacket;
(c) compacting said powder by cold pressing the powder in the jacket;
(d) forming the open end of the jacket into a truncated parabellum; and
(e) filling the jacket by injecting a metal-loaded polymer therein and forming a tip of said metal-loaded polymer on the projectile exterior to the truncated parabellum.
In preferred embodiments of the method of the invention, the projectile is a bullet.
In further embodiments, the jacket is a copper jacket.
In still further embodiments, the metal powder is copper or tungsten.
In another embodiment, the metal-filled polymer is an amorphous or low crystallinity polymer, especially ethylene/methacrylic acid copolymer ionomer, polyetherester elastomers or polyamide, filled with particles of copper, tungsten, bismuth, tin and/or stainless steel.
A further aspect of the invention provides a method of forming a lead-free projectile, comprising:
(a) placing a pre-formed open ended metal jacket in a mould, said jacket being formable under pressure;
(b) partially filling the jacket by injecting a metal-loaded polymer therein;
(c) adding metal powder into said jacket;
(d) compacting said powder by cold pressing the powder in the jacket; and
(e) closing the open end of the jacket.
In embodiments of the method, the jacket has a pre-formed truncated parabellum, and a tip of said metal-loaded polymer is formed on the projectile in step (b).
In preferred embodiments of the method of the invention, the projectile is a bullet.
In further embodiments, the jacket is a copper jacket.
In still further embodiments, the metal powder is copper or tungsten.
In another embodiment, the metal-filled polymer is an amorphous or low crystallinity polymer, especially ethylene/methacrylic acid copolymer ionomer, polyetherester elastomers or polyamide, filled with particles of copper, tungsten, bismuth, tin and/or stainless steel.
In another aspect of the invention, there is provided a lead free projectile comprising a preformed metal jacket having an open end and a closed tip end, said metal jacket being filled with cold-pressed powder and said open end being sealed with a metal filled polymer.
In a preferred embodiment, the open end of said jacket curves inward to retain the polymer over the powder.
In a further aspect of the invention, there is provided a method of forming a lead-free projectile, comprising:
a) providing a pre-formed metal jacket, having an open end and a closed tip end;
b) adding a predetermined amount of metal powder into the jacket through the open end;
c) compacting said powder by cold-pressing the powder in the jacket; and
d) filling the jacket with a metal-loaded polymer thereby closing the open end.
The present invention is illustrated by the embodiment shown in the drawings, in which:
The present invention relates to a lead-free projectile, and especially to a lead-free projectile that has an increased weight (grain) compared to other lead-free projectiles of the same size. The invention also relates to the method of forming the projectile.
Examples of ethylene/methacrylic acid copolymer ionomers are ethylene/methacrylic acid copolymers that have been partially neutralized with metals ions such as sodium or zinc. Such polymers are available from E.l. du Pont de Nemours and Company under the trademark Surlyn. It is preferred that the ionomer not be too viscous, for ease of dispersion of filler particles in the composition e.g. have a melt index of at least 5; melt index is measured by the procedure of ASTM 1238. Examples of polyamides include nylon 11, nylon 12, nylon 12/12 and related amorphous or low crystallinity polyamides. The polymer may also be a polyetherester elastomer e.g. an elastomer available from E.l. du Pont de Nemours and Company under the trademark Hytrel. Blends of such polymers or of such polymers with other polymers to provide amorphous or low crystallinity polymers may also be used.
The method discussed with reference to
The method above has been described herein with reference to the method shown in
The projectile described above has a metal-filled polymer as the tip. Such a tip would be expected to fracture on impact with an object. In addition, the projectile has a substantial component that is composed of loosely bonded metal particles. Thus, on hitting a hard object, the projectile would be expected to disintegrate, and therefore would not be expected to ricochet. All parts of the projectile would be expected to disintegrate and/or turn to powder, including the jacket.
Examples of ethylene/methacrylic acid copolymer ionomers are ethylene/methacrylic acid copolymers that have been partially neutralized with metals ions such as sodium or zinc. Such polymers are available from E.l. du Pont de Nemours and Company under the trademark Surlyn. It is preferred that the ionomer not be too viscous, for ease of dispersion of filler particles in the composition e.g. have a melt index of at least 5; melt index is measured by the procedure of ASTM 1238. Examples of polyamides include nylon 11, nylon 12, nylon 12/12 and related amorphous or low crystallinity polyamides. The polymer may also be a polyetherester elastomer e.g. an elastomer available from E.l. du Pont de Nemours and Company under the trademark Hytrel. Blends of such polymers or of such polymers with other polymers to provide amorphous or low crystallinity polymers may also be used.
The present invention is illustrated by the following example.
Projectiles in the form of 0.223 calibre (5.56 mm) bullets were made in two different weights, 58 grains and 63 grains.
The 58 grain bullet had a copper jacket weighing 19 grains, copper powder weighing 33 grains and copper-filled ionomer weighing 6 grains. The copper-filled ionomer had greater than 90% by weight of copper and less than 10% by weight of ionomer.
The 63 grain bullet had a copper jacket weighing 19 grains, a mixture of copper and tungsten powder weighing 38 grains and copper-filled ionomer weighing 6 grains. The copper-filled ionomer had greater than 90% by weight of copper and less than 10% by weight of ionomer.
The bullets were formed using the process described above. The metal powder was metered into the jacket, which had an open top and a square bottom. The metal powder was cold pressed into the jacket. The filled jacket was then placed into a mould of an injection moulding apparatus. The apparatus was designed so that when the mould was closed, the top of the jacket was formed into a truncated parabellum. The metal-filled polymer was then injected into the jacket, using an injection moulding process, at which time the tip of the bullet was formed.
Both types of bullets were assembled in the form of live ammunition and fired at a target using a number of weapons. Both types of bullets were very accurate, and performed as well as or better than commercial lead bullets of the same calibre. The bullets turned to powder when fired at a steel plate, thereby demonstrating anti-ricochet properties of the bullets.
This application is a National Stage entry of International Application No. PCT/CA02/00583, filed on Apr. 24, 2002, the entire specification, claims, and drawings of which are incorporated herewith by reference; which claims benefit from provisional U.S. Application No. 60/286,172, filed on Apr. 24, 2002.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CA02/00583 | 4/24/2002 | WO | 00 | 3/4/2004 |
Publishing Document | Publishing Date | Country | Kind |
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WO02/086412 | 10/31/2002 | WO | A |
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