Raimey,
The caliber is likely some version of 10x52, but there is not enough info for ID. The 15 gram bullet would be 231.5 grains, which could fit into a MB base, 360 base, or M88 base cartridge. With a lead bullet, I wouldn't think it would be M88 base, but maybe LK. Need chamber cast, barrel slug. Note nitro proof.
Mike

Last edited by Der Ami; 05/08/19 09:47 AM.