B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
B21K21/00—Making hollow articles not covered by a single preceding sub-group
B21K21/04—Shaping thin-walled hollow articles, e.g. cartridges
B—PERFORMING OPERATIONS; TRANSPORTING
B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
B21D51/00—Making hollow objects
B21D51/16—Making hollow objects characterised by the use of the objects
B21D51/54—Making hollow objects characterised by the use of the objects cartridge cases, e.g. for ammunition, for letter carriers in pneumatic-tube plants