This reloadable shotshell in 12 gauge seems to have been made at Sevilla by an unknown (to me) manufacturer.
The case is very heavy, with thick walls, but I couldn’t say if it was made from a brass bar or by drawing a brass cup. It measures 54.5 mm.
The headstamp reads (C P.P.T 12 SEVILLA).
The Palencia factory of the Santa B