Importance

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Abstract

A method is taught of manufacturing cartridge cases having a substantially cylindrical outer side wall surface and a tapered inner side wall surface. The method comprises the steps of initially forming a cup-shaped article having substantially cylindrical inner and outer side wall surfaces, a substantially flat outer bottom surface with an annular chamfered surface joining the flat outer bottom surface to the outer side wall and an inner bottom wall surface. Thereafter, the cup-shaped article is engaged by a punch element and the punch element forces the cup-shaped article through a series of die members without any intermediate annealing of the article after passage through any of the die members. The punch element has an outer side wall and a bottom wall, the bottom wall being dimensioned so that the diameter of the peripheral edge of the bottom wall is substantially the same as the diameter of the peripheral edge of the inner bottom wall surface of said cup-shaped article whereby at least the peripheral edge of the bottom wall of the punch element will contact the peripheral edge of the inner bottom wall surface of the cup-shaped article when the punch element engages the cup-shaped article to thereby align the punch element and the cup-shaped article with one another for forcing the cup-shaped article through the series of die members. The side wall of the punch element is tapered so as to correspond in configuration and dimension to the configuration and dimension of the tapered side wall surface of the cartridge case to be formed. The die members, the cup-shaped article, and the punch element are dimensioned so that the cup-shaped article is only subjected to ironing during passage through the die members to thereby increase the length of the side wall of the cup-shaped article while reducing the thickness of the side wall thereof.

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First Claim