That has GOT to be an early smokeless than.

I cut my 12 TPI square threads for them with a .043" grooving insert and yes, they visibly come across as WAY narrower than the Springfield Arsenal 10 TPI square threads on everything from the trapdoor onward through WW1.

FWIW, Sharps chose the 10 TPI, for their barrel shanks, too.

GTC

Member, Clan of the Border Rats
-- “Sometimes I wonder whether the world is being run by smart people who are putting us on or by imbeciles who really mean it.”- Mark Twain