Originally Posted by Drew Hause
Chamber entrance of .856" is the 10 gauge standard.
.760" bore would have been marked 11/1 at the time of proof.


Well, 21.75/25.4 (metric) works out to .856.

As for the muzzle inner diameter, remember that's at street howitzer length. Who knows how tight it was when it left the factory full length (whatever that may have been).

Chambered 10 gauge choked 12 gauge is something I've never heard of before [ETA; .690 is normal 12 gauge full choke - had to look that one up]

Last edited by Story; 10/20/22 03:26 PM.