Ammunition and explosives – Projectiles – Composite
Reexamination Certificate
1998-11-24
2002-10-01
Jenkins, Daniel J. (Department: 1742)
Ammunition and explosives
Projectiles
Composite
Reexamination Certificate
active
06457417
ABSTRACT:
FIELD OF INVENTION
This application relates to the manufacture of projectiles for use in small bore gun ammunition and to the projectiles obtained thereby.
BACKGROUND OF INVENTION
In the present application “small-bore” weapons are defined as those weapons of .50 caliber or smaller caliber. The weapon may be a pistol or rifle which includes a rifled barrel.
As used herein, the term “heavy metal” refers to a metal having a density greater than the density of lead and the term “light metal” refers to a metal having a density equal to or less than the density of lead. “Heavy metal-based”, as used herein, refers to a product which comprises a significant portion, commonly 50% but can be as low as about 20%, by weight, of a heavy metal.
A projectile for a small bore, i.e., .50 caliber or less, weapon having a rifled barrel, commonly, has heretofore been formed from lead. Lead, and similar soft metal projectiles tend to leave deposits of the metal within the barrel of a weapon as the projectile is propelled along the barrel during firing of the weapon. In such jacketed lead-based projectiles, the trailing end of the lead is not fully covered by the inwardly folded open end of the jacket so that this end of the lead is exposed to the heat and pressure of the burning powder of an ammunition cartridge. Under these circumstances, a portion of the trailing end of the lead is volatilized and eventually condenses in the gun barrel, leaving the barrel fouled with lead. In the prior art, it has been a common practice to encase the lead projectile in a copper jacket to eliminate contact of the lead with the lands and/or inner wall of the weapon barrel, and thereby eliminate the lead deposits within the barrel. These copper jackets are commonly preformed, loaded with a lead core, and thereafter die formed to shape the core and jacket into the desired geometry for the projectile. Lead, being highly malleable, readily deforms to the contour of such dies without fracturing. It has also been practiced to electroplate a copper coating on the exterior surface of a lead core. U.S. Pat. No. 5,597,975 references certain prior copper-plating art and discloses a further plating process for ammunition projectiles. Notably, the cores of these prior art projectiles are not intended to be frangible, hence they generally generate only a channel into or through a target. These projectiles, therefore, have less than desired ability to deliver a stopping force to a moving target, such as an animal.
In known prior art jacketed ammunition projectiles, it has been the intent that the jacket play a material part in the destructive force delivered by the projectile to a target, e.g., the terminal ballistics of the projectile. Accordingly, in the prior art, commonly the jackets are locked onto the core by various mechanical interlocks between the jacket and core, such as channelures and other spatially separated indentations in the core and overlying jacket. In similar manner, heretofore, the prior art teaches that the coating applied to a core for use in forming projectiles should perform a destructive function upon the projectile striking a target. Hollow point type projectiles are of this type. Thus, in some prior art coated or jacketed lead-based projectiles, the jacket or plate coating is scored or otherwise treated to encourage the jacket or coating to fragment upon the projectile striking a target and thereby enhance the “stopping power” (ie., terminal ballistics) of the projectile. Even under these circumstances, the lead core does not materially fragment.
Because of environmental concerns relating to lead, much effort has been expended in the development of projectiles which do not contain lead. This effort has attempted to fabricate a projectile which, when fired from a weapon, responds as nearly like a lead projectile as possible. By this means, there need be little or no change in either existing guns or in the ammunition for these existing guns. Further, there is little or no need to retrain shooters in the use of new and different ammunition. Metals having a density greater than the density of lead generally do not lend themselves to known manufacturing techniques for projectiles for gun ammunition. In part, the expense associated with working with such metals has led to the use of powders of heavy metals. These powders, in general, are difficult to form into shapes. Combinations of various heavy metal powders with lighter metal powders that function as binders for the heavy metal powders have been suggested. Among these combinations it has been suggested that tungsten powder be combined with tin powder and cold-pressed into a projectile, such as in U.S. Pat. No. 5,760,331. Other similar powder combinations have been suggested. Coating or plating the individual powder particles has also been suggested to obtain enhanced packing of the powder particles in a die or to render these individual powder particles non-abrasive. These projectiles suffer various deficiencies including, among others, abrasion of the barrel of the weapon including abrasion and eventual failure of the gas system employed to operate the bolt of an automatic or semi-automatic weapon, inaccuracy of flight to a target, inconsistency of performance from projectile to projectile, high cost of manufacture, incomplete frangibility, etc.
Aside from the reported adverse effects of lead projectiles, in certain shooting situations, such as competitive shooting, sport shooting, and certain warfare and/or law enforcement situations, there has developed a need for a projectile of special properties. For example, accuracy of delivery of the projectile from a weapon to a target has always been a concern of shooters of all classes. Wind effects upon a projectile during its free flight to a target can seriously divert a projectile from its desired flight path, the degree of diversion for a given projectile being a function of the strength and direction of the wind, among other factors. It is known in the art that a heavier projectile offers greater resistance to its flight deviation due to wind effects, but heavier projectiles for a given caliber present other problems. For example, heavier projectiles of a given caliber can be made larger (i.e. longer), but to enable a round of ammunition to be chambered in a given caliber weapon, especially in automatic or semi-automatic guns where the overall length (OAL) of a cartridge must be compatible with the magazine for the gun and the chambering mechanism for the gun, the overall length of the round cannot exceed a given standard value, so that any extra length of a heavier projectile must be disposed within the interior of the case of the round of ammunition. This reduces the space available with the interior of the case which is available to receive gun powder. Less gun powder and a heavier projectile result is a slower moving projectile which, in turn, results in several shooting disadvantages, among which is the fact that the projectile will more easily be adversely affected by wind and static air penetration factors, and the projectile will assume a more pronounced trajectory in its travel to a target and will strike the target at a relatively lower velocity, and with reduced terminal ballistics, for example. Further, spin stability of such projectiles becomes a major factor with respect to the accuracy of the flight of the projectile to its target, in some instances requaireing the barrel of the weapon to be provided with a greater twist value that will ensure spin stability of the projectile.
Alternatively, heavier projectiles of a given caliber can be fabricated from a metal that is heavier than lead. Uranium, tungsten, tantalum and tungsten carbide, for example, have been suggested candidates for heavy projectiles. Herein the term “heavy metal” is intended to include carbides of the metal unless the context of use clearly indicates otherwise. These metals and their carbides are difficult and expensive to fabricate into a projectile, hence, as noted above, powder metallurgy techniques have been sugg
Doris Nebel Beal Inter Vivos Patent Trust
Jenkins Daniel J.
Pitts & Brittian P.C.
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