Oh I shot it! Special thanks to Mr. Hallquist and Parabola. It used one of the first brass cartridges Mr. Hallquist provided me a picture of one. ( he can share his pic if he wishes, since there doesn’t seem to be any others)Looks to have used a cap not primer in center ( hence flat firing pins). Chamber is pretty much a 14ga chamber,bores are .726 no pits only slight frosting ( it’s original). I shot some 6-7k psi 16ga rio reloads and it surprisingly patterned quite well at 23yds. It looks like RMC can make brass the will work fine but it would be much easier to open up chamber and rim recess for a modern 12. Some paper 12ga 800x 1 1/8 oz at 5500 psi would make it a blast to hunt with.
[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]

Last edited by Jtplumb; 10/01/23 08:18 PM.