Ammunition and explosives – Projectiles – Composite
Reexamination Certificate
2000-10-11
2003-05-20
Johnson, Stephen M. (Department: 3641)
Ammunition and explosives
Projectiles
Composite
C102S439000
Reexamination Certificate
active
06564720
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to firearms ammunition, and more particularly to sabots for use with shotguns, muzzle-loading rifles, and the like.
(2) Description of the Related Art
The use of slugs with shotguns is intertwined with the history of shotguns themselves. U.S. Pat. No. 3,726,231 discloses a waisted slug known as the BRI slug or bullet. Such waisted slugs grew to prominence in the 1970's and 80's. That time period saw increased interest in use of shotgun slug motivated by a combination of user preference and regulatory influence. The availability of rifled shotgun barrels also increased, further enhancing slug performance.
In parallel, the field of muzzle-loading rifles continues to flourish with a dedicated following. This field also provides fertile ground for use of saboted projectiles.
There are ongoing development efforts in saboted projectile technology. U.S. Pat. No. 5,214,238 discloses a sabot for chambering conventional bullets in a shotgun. U.S. Pat. No. 5,415,102 discloses a muzzle loading sabot. General dimensions of shotshells and pistol bullets are respectively disclosed in
American National Standard Voluntary Industry Performance Standards for Pressure and Velocity of Shotshell Ammunition for the Use of Commercial Manufacturers and in Voluntary Industry Performance Standards for Pressure and Velocity of Centerfire Pistol and Revolver Ammunition for the Use of Commercial Manufacturers
ANSI/SAAMI Z299.2-1992 and Z299.3-1993 (American National Standards Institute, New York, N.Y.).
There, however, remains room for further improvement in the field.
BRIEF SUMMARY OF THE INVENTION
Accordingly, in one aspect, the invention is directed to a sabot for firing a subcaliber projectile from a firearm. The sabot includes a molded member, preferably formed of a plastic. The molded member includes a base and a number of petals each extending forward from a proximal root at the base to a distal tip. Each petal cooperates with the base to define a volume for accommodating the projectile in a pre-firing condition. A reinforcement is at least partially embedded in the base and is more rigid than the molded member. The reinforcement includes fore and aft faces and a lateral perimeter. The reinforcement includes a central aperture along a central longitudinal axis of the projectile and a number of additional apertures. The material of the base portion extends through the additional apertures and is effective to retain the reinforcement within the molded member upon firing.
In implementations of the invention, the reinforcement is preferably metal. The additional apertures are preferably chamfered at least at the fore face. The base preferably includes a centrally-apertured web along the reinforcement fore face. The reinforcement perimeter preferably extends beneath the roots of the petals. There may be exactly four petals separated from each other by four circumferential gaps extending between sabot interior and exterior circumferential surfaces. Each petal may have inboard and outboard surface portions and a pair of connecting surfaces along the adjacent gaps. The gaps may be substantially wider at the exterior circumferential surface than at the interior circumferential surface.
The molded member may consist essentially of a polyethylene while the reinforcement may be a pressed iron-based material. The petal inboard surface portions may include a proximal portion with a first diameter effective to cooperate with a cylindrical body of the projectile and a distal portion formed as a protuberance having a surface portion for engaging an ogive of the projectile. Such surface portion may be of circumferential extent smaller in angle than the proximal portion. The adjacent connecting surfaces of adjacent petals may be substantially flat and oriented relative to each other at an angle of between 80 and 100 degrees about the central axis. The projectile may be an ogival hollow-point bullet of maximum diameter between 0.4200 inch and 0.5100 inch or, more narrowly, 0.4300 inch and 0.5100 inch. The saboted projectile may be loaded in a shotshell hull with propellant, a shotshell primer, and wadding to form a loaded shell. The shell may be dimensioned for firing from a 20-gauge or a 12-gauge shotgun. The projectile may be a partition bullet having a front core and a rear core which is harder than the front core. The rear core may comprise a lead-antimony alloy and the front core may comprise a lead-based material. The alloy may have at least 2% antimony, by weight, whereas the front core material may preferably have less than 1% antimony. The sabot may be dimensioned for firing from a 12 gauge shotgun while the bullet may be a 0.50 caliber secant ogive partition bullet.
In another aspect, the invention is directed to a method for manufacturing a saboted bullet. A bullet is provided. A reinforcement is provided having a plurality of apertures. The reinforcement is held and the sabot body is molded therearound so that material from the sabot body flows into the apertures and extends therethrough so as to link a portion of the body forward of the reinforcement to a portion of the body after the reinforcement. The bullet is inserted into the sabot body through a fore end thereof.
In various implementation of the invention, the bullet may have a nominal caliber of 0.44, .45, or 0.50. The sabot may have dimensions effective to fire the bullet from a 20-gauge shotgun if the bullet is 0.44 or 0.45 caliber or a 12-gauge shotgun if the bullet is 0.50 caliber. The step of inserting may cause the bullet to flex petals of the sabot outward as the bullet enters the sabot and then allow the petals to at least partially return to an unflexed condition as the bullet nears a fully-installed position.
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The Shotgun Slug Revolution, Bryce M. Townsley,American Rifleman, vol. 148, No. 3; pp. 4,30-33, and 66; Mar. 2000.
Eberhart Gerald T.
Gardner Robert J.
Meyer Stephen W.
Johnson Stephen M.
Olin Corporation
Rosenblatt Gregory S.
Wiggin & Dana LLP
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