Sheet metals are usually purchased at the proper temper ready to be sheared or cut into blanks, but in drawing tubes or shells the action of the tools rapidly hardens the metal, thereby making it necessary to anneal the metal a number of times according to the number of operations or processes that the metal is passed through to produce the finished article. A cartridge case for a 6 in. quick-firing gun would be 16 in. long, tapering from 7 in. diameter at the breech end to 6.5 in. diameter at the muzzle end; such a metal shell would be made from a blank 12f in. diameter by 3/4 in. thick and weighing 28 1/2 lb. It is formed into the thin case or shell by successive drawings, annealings, pressings, and