Ammunition and explosives – Projectiles – Dumdum or mushrooming
Reexamination Certificate
2003-04-23
2004-05-11
Tudor, Harold J. (Department: 3641)
Ammunition and explosives
Projectiles
Dumdum or mushrooming
C102S517000
Reexamination Certificate
active
06732657
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a method of manufacturing a soft point or soft nose bullet and the bullet resulting from the method.
Jacketed or plated soft point bullets are generally well known. In such bullets a core of soft metal such as lead or a lead alloy is plated with a jacket of copper or copper alloy. The copper or a copper alloy provides a degree of lubrication for the bullet as it passes through the rifling of a gun barrel. This minimizes damage which would otherwise occur to the barrel with a solid lead bullet. The jacket further maintains the integrity of the bullet intact as the soft point expands on impact.
As discussed in U.S. Pat. No. 4,387,492 for a “Plated Jacket Soft Point Bullet”, it is common to produce soft point bullets by making a cup-shaped jacket of copper or the like, and by inserting a core from a base metal such as lead. Nose weakening features may be added to the bullet nose in subsequent operations to produce a soft point bullet. This prior technique resulted in several problems including the potential for separation of the core from the jacketing material.
Conventional bullet fabrication techniques further produce inconsistencies in shape and weight that can cause inaccurate flight of the bullet. Prior methods required trimming and matching in an effort to mate the right weight and size core with the right weight and size outer jacket. The nose weakening features to induce expansion of the bullet typically are sliced or drawn into the outer jacket of the bullet. These operations usually required additional machining and could introduce eccentricity in a bullet that could detrimentally affect its use.
The method disclosed in the above noted U.S. Pat. No. 4,387,492 improved upon conventional bullet-making techniques by electroplating the material such as copper to the lead core which had been shaped to the proximate size and shape of the bullet. The electroplated material and part of the soft core is then sheared from the forward end of the core and the bullet is reshaped into the final shape. This improved forming operation produces an unplated forward portion of the bullet which would expand upon impact. The use of such shearing techniques to expose the softer core of the bullet tip, however, could cause distortion and thickening of the outer jacket of the bullet and affect the bullet performance. U.S. Pat. No. 5,079,814 also discloses a technique for making a hollow point bullet by electroplating the jacket to the core.
An object of this invention is to provide a method of manufacturing a soft point bullet and an improved bullet resulting from such method which overcomes many of the disadvantages of prior art methods and devices.
A further object of this invention is to provide an improved method for manufacturing a soft point bullet which minimizes the distortion and thickening of the bullet jacket and lessens the inaccuracies common to prior operations. An object of the invention also is to simplify bullet fabrication by reducing or eliminating the need for jacket trimming and weight matching to produce the final bullet.
An additional object of this invention is to provide a method of making a soft point bullet that does not materially change the weight of the bullet during manufacture and results in little or no scrap material.
A still further object is to provide a method of manufacturing a soft point bullet and the bullet itself which allows for the regulation of the expansion of the bullet when the bullet impacts a target.
Another object of this invention is to provide a method of making soft point bullets which is readily adaptable to make bullets having a small caliber.
In accordance with the present invention, the method of manufacturing a soft point bullet includes the step of forming a core of a soft material such as lead or a lead alloy, e.g., lead and antimony, into a selected shape, preferably a generally right cylinder. The core of soft material is then plated with a plating material such as copper or copper alloy to form a plated core of a selected geometric shape. The plated core is then fed into a forming machine and one end of the plated core is subjected to an operation, such as punching, to form a cavity in the one end. In the preferred embodiment the cavity is polygonal in shape and has a generally flat face. A six-sided polygonal cavity is preferred, but a cavity with three to ten sides can be used for different ballistic requirements for the bullets. The length or depth of the cavity can be selected to suit the size of the bullet and produce the desired operating characteristics. The side walls of the cavity can be straight or tapered inwardly to slightly narrow the cavity in a direction away from the one end of the bullet. Other tool or die shapes also can be used to produce the desired cavity having a plurality of spaced surfaces. The method in accordance with this invention provides multiple notches or cuts in the plated material spaced around the periphery of the cavity and defines multiple fracture points spaced generally uniformly around the nose of the bullet.
This forming operation also drives a pointed or polygonal blank of the plating material into the interior of the soft core at the lower portion of the cavity. The position of the blank is determined by the depth of the cavity, and can be adjusted by changing the penetration of the tool used to create the cavity.
The resulting blanked core formed by the above process is further formed under pressure, such as by swaging, to extrude the soft core material around the pointed or polygonal material blank positioned within the core. This pressure also extrudes the soft material of the core into the cavity and shapes the plating material to form the blanked core into a soft point bullet having a conical tip or ogive on the one end. The bullet is then subjected to finishing operations such as tumbling and polishing to form the final soft point bullet.
The soft point bullet manufactured in accordance with this invention includes a soft material core made from, for example, a metal such as lead or a lead alloy, that is plated with a jacket of a harder material, such as copper or copper alloy. Multiple fracture points are formed into the plated jacket at the nose of the bullet. These fracture points are generally spaced uniformly around the front end of the bullet and allow the bullet to expand or mushroom upon impact with the target. The polygonal shaped blank of plating material retained within the core toward the nose becomes generally dome-shaped during manufacture. The extent of the reshaping of the blank into a domed shape depends upon the diameter of the bullet. The blank inside the core operates as an expansion regulation for the bullet. Tooling and process adjustments can be made to vary the size, shape and depth of the blank within the core and to allow for the alteration of the expansion characteristics of the bullet to meet specific performance requirements.
REFERENCES:
patent: 1134797 (1915-04-01), Wood
patent: 1838645 (1931-11-01), Hartz
patent: 2327950 (1943-08-01), Whipple
patent: 3173371 (1965-03-01), Manshel
patent: 3431612 (1969-03-01), Darigo et al.
patent: 4387492 (1983-06-01), Inman
patent: 4879953 (1989-11-01), Carter
patent: 4882822 (1989-11-01), Burczynski
patent: 4947755 (1990-08-01), Burczynski
patent: 5079814 (1992-01-01), Moore et al.
patent: 5185495 (1993-02-01), Petrovich et al.
patent: 5365853 (1994-11-01), Petrovich et al.
Alliant Techsystems Inc.
Brinks Hofer Gilson & Lione
Tudor Harold J.
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