COMMERCIAL cases of whatever type — rimless, rimmed, belted, semi-rimmed, centrefire or rimfire — are generally made of brass, with few exceptions. There are low-pressure rimfire cases made of copper. Shotgun cases nowadays are plastic; few are made of paper and brass anymore. The Germans made many military cases of steel during both the first and second World Wars, and the Americans made many in .30-06 and .45 ACP. Today, there is some Russian ammunition with cases made of steel.
Cartridge brass is actually an alloy, composed of about 70 percent copper and 30 percent zinc. Some common American brands may include a trace of silver, and alloy proportions may vary for a few tenths of a percent. Cases for premium ammunition may have a plating of nickel, but they are still brass and are treated as such in all reloading procedures.
Cases are made from sheet brass. Each disc that is stamped out is formed into a cup, and gradually formed into the completed case by a series of dies. The brass should be good and clean to start with, but the care taken in working it determines its eventual strength. Working brass makes it hard and brittle, so as the case goes through a series
