All Plastic Polycarbonate Shot Shell With Star Crimp

Abstract

A plastic molded one piece shot shell case entirely of plastic and with the open mouth end reduced in thickness by molding and formed in a star crimp to close the case and confine the shot and powder.

Description

BRIEF DESCRIPTION OF THE INVENTION

It has recently been found possible to manufacture shotgun shells with an all plastic one piece molded shot shell case. Such cases are molded entirely in one piece of plastic. The plastics used must have sufficient tensile, sheer and impact strength as to withstand the pressures encountered in the chamber of a shotgun upon firing the shot shell, and must be capable of being bent or crimped numerous times to facilitate repeated loading, crimping, firing and reloading. Polycarbonate plastics are satisfactory, and it has been found desirable in certain instances to mix eight to ten per cent by weight of polyethylene into the polycarbonate. Such polycarbonates are made by several manufacturers under several names, such as Lexan by General Electric Company of Schenectady, New York, and Merion by Mobay Chemical Company of Pittsburgh Pennsylvania. Where, herein, the terminology plastic or all plastic is used with reference to such shot shell cases, it is intended to include such materials or mixtures of materials as described above.

Heretofore polycarbonate plastic has been considered stiff and tough, but it has not been acknowledged to have any properties of being bendable and returnable to its original shape. Applicants, in molding shot shell cases from plastic, have been informed by all of the experts in the field of plastics that it is impossible to make any sharp bends in this material with any expectancy that such material would assume its original shape. As a result, it has been common in the past to close such all plastic shot shell cases by means of a closure wad or end disc and a very slight crimp or taper at the mouth end of the shot shell case.

Applicants have found that, after a considerable amount of work in this forming of all plastic shot shell cases, under certain circumstances hereinafter set forth, it is possible to make a star crimp in a plastic shot shell case so that the case can be reloaded and reclosed eight or ten or more times.

An object of this invention is to devise a construction of an all plastic case wherein the mouth end of the shot shell case can be closed with a star crimp and then reopened upon firing and then reclosed again upon reloading through a number of reloadings so that maximum use can be obtained of the case.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an elevation view of a loaded shot shell, partly broken away for clarity of detail, made according to the present invention.

FIG. 2 is an end elevation view of the closed shot shell case illustrated in FIG. 1 and showing the star crimp which has been formed.

FIG. 3 is a detail section view of the mouth end of the shot shell case formed according to the present invention and adapted for forming of the star crimp.

DETAILED DESCRIPTION OF THE INVENTION

The all plastic shot shell case 10 in FIG. 1 is seen to be loaded and closed and ready for firing. In the cutaway portion in the drawing, the shot 11 is seen to fill up the upper spaces of the case, into the area of the closure 12, and a conventional shot cup 13 is also provided in the case to hold the shot charge. The closure 12 will be seen to be a star crimp, and in this particular crimp the star has six folds, but the star crimp could as well have eight or 12 folds. In FIG. 3 the open mouth of an empty shot shell case 10 is seen in section and it will be noted that the upper portion 14 of the case wall, around the entire periphery of the case wall, is tapered to a reduced thickness, immediately adjacent the end edge. The taper at 14 in the case wall is formed during the molding process so that the wall 10 is uniform in consistency as to the plastic and without any stress lines throughout the entire length thereof. The molded taper facilitates the inward folding of the end of the case wall into the star crimp as seen in FIGS. 1 and 2.

It is to be particularly noted that, in forming a star crimp of the tapered end of the case wall of plastic, the tapered portion 14 of the wall is simply folded directly inwardly in the star crimp folds, and without any folding of the wall downwardly back upon itself to form a peripheral bead or crimp around the edge of the star crimp closure 12. Preferably the tapered end portion 14 of the case wall is turned inwardly at approximately 90.degree., but it is also preferred that the fold inwardly not exceed 90.degree.. In most instances, it is not necessary to force the tapered portion of the plastic case wall so as to obtain a full 90.degree. bend, but it is suitable in many instances, as in the case where a shooter is reloading his own ammunition, to let the star crimp bulge or taper slightly upwardly a few degrees, less than 5.degree., from the horizontal position illustrated in FIG. 1.

It has been found that when using the star crimp in the all plastic shot shell case, the case wall will withstand numerous firings and it has been found that the case may be reloaded as many as eight or ten times with regularity.

By way of example, the plastic case wall is approximately thirty thousandths of an inch thick immediately below the tapered portion 14 of the case wall and the wall is tapered at the inner side as seen, down to a thickness of approximately twenty thousandths of an inch.

The exterior periphery of the case wall is substantially cylindrical upon molding so that when the closure 12 opens upon firing of the shotgun shells, the outer periphery of the case wall will lay flat against the interior periphery of the shell chamber in the barrel of the gun. The taper will further minimize damage to the mouth portion of the case wall upon the ejecting of the shot and wadding from the shotgun shell upon firing.

It will be seen that we have provided a new and improved all plastic shot shell case construction facilitating star crimping of the all plastic shot shell case by molding in a taper adjacent the mouth of the case wall to accommodate the folding and inward bending so that the closure portions of the case wall form approximately a 90.degree. bend with the cylindrical peripheral portions of the case wall.

Claims

What we claim is:

1. A charged shot shell having an all plastic case comprising:

a molded polycarbonate plastic case with substantial stiffness and tensile strength, the tubular wall of the case having a substantially cylindrical outer surface, and the wall having a star crimp formed at the open mouth end of the case wall to confine the charge of the shot shell, the case wall having a bend at the periphery of the star crimp and adjacent the substantially cylindrical wall and the crimped mouth portion of the case extending evenly radially along the crimp folds and then smoothly joining the cylindrical case wall at said bend, the case wall being tapered at the inner surface thereof from a location below said bend and toward the end edge of the open mouth of the shot shell case wall, said all plastic case wall being reduced progressively in thickness at said bend and toward the open mouth therefrom, the wall being tapered in thickness to substantially a minimum adjacent the end edge at the open mouth, the being being no more than 90.degree. to minimize the folding of the case wall at the periphery of the star crimp, the bend at the periphery of the star crimp being rounded and not sharply angular, and the plastic case wall extending from said bend away from each other and along the case wall and into the star crimp and not being folded back upon itself.