CPC Subgroup
B21K 21/04 Shaping thin-walled hollow articles, e.g. cartridges
Full Title
Making hollow articles not covered by a single preceding sub-group (essentially from sheet-metal or uniform thin-walled tubes B21D, e.g. B21D41/00, B21D51/00) > Shaping thin-walled hollow articles, e.g. cartridges