Victor Collette Cape Gun ammo question

[Zed]

I'm hoping that somebody might be able to identify a mystery caliber.

A friend bought a cape gun which has a 12 gauge shotgun barrel and an unlabeled rifle barrel. He made a casting of the rifle chamber, with the attached results.

He has a .375 Flanged Nitro Express cartridge, which is close, but not the exact cartridge.

Any suggestions as to caliber and/or to a reference book that would confirm the caliber ?

Thanks for your help

Z

 

[Dosing]

try the forum at IAA https://forum.cartridgecollectors.org/

 

[DiMP]

I'm looking through the tables at the back of the "Cartridges of the World" and can't find a match? Nothing close in the .320-.333 bullet diameter. If I think about it I'll bring the book out while drinking coffee in the next few days and look again with fresh eyes