Method of making shell casings

Claim 1

IN A PROCESS OF DRAWING A STEEL CARTRIDGE CASING FROM A BLANK, THE STEPS OF SHAPING THE BLANK INTO A SUBSTANTIALLY CIRCULAR DISC HAVING A THICKENED CENTER WITH AN ANNULAR MARGINAL PORTION TAPERING AWAYS FROM THE CENTER TOWARD THE PERIPHERY OF THE DISC, DRAWING AND CUPPING THE DISC TO FROM A CUP WITH THICKENED CENTER SUBSTANTIALLY AT THE BASE AND THE TAPERED PORTION IN THE CYLINDRICAL WALL OF THE CUP, PROGRESSIVELY DRAWING THE WALL OF THE CUP TO ELONGATE THE SAME WITH A THICKENED WALL PORTION ADJACENT AND MERGING INTO THE BASE OF THE CUP, BULDGING SAID THICKENED WALL PORTON RADIALLY OUTWARDLY PROGRESSIVELY DRAWING SAID BULGED PORTION AWAY FROM THE BASE THE WALL TO COLD WORK THE WALL PORTION IMMEDIATELY ABOVE THE BASE, PERFORATION THE BASE, PLUNGING THE LOWER PART OF THE CASING INCLUDING SAID COLD WORKED WALL PORTION INTO A HEAT TREATING BATH AT A TEMPERATURE IN THE VICINITY OF THE AC3 POINT FOR A SUFFICIENTLY