I'm thinking .380 in a 9x18 barrel is POSSIBLE, just not " optimal"... An emergency expedient, MAYBE... Not accurate, reliable or as powerful... Probably have feeding & extraction issues.
The other way around?? Bad juju to jam a too long case with a slightly wider diameter bullet ...best to buy two guns, conversion kits& tools or to come up with a new design like I suggested... I could theoretically see a mid sized , locked breech multi caliber& barrel pistol as workable... Definitely. 380 & 9x18 would be doable. Maybe 9x19 and other calibers..depends on size, lockwork, complexity of design vs simplicity.
Maybe a slightly enlarged ( compared to a Makarov PM _ CZ82 with a locked breech, or even a Glock.
The other way around?? Bad juju to jam a too long case with a slightly wider diameter bullet ...best to buy two guns, conversion kits& tools or to come up with a new design like I suggested... I could theoretically see a mid sized , locked breech multi caliber& barrel pistol as workable... Definitely. 380 & 9x18 would be doable. Maybe 9x19 and other calibers..depends on size, lockwork, complexity of design vs simplicity.
Maybe a slightly enlarged ( compared to a Makarov PM _ CZ82 with a locked breech, or even a Glock.