J Stevens 410 bore or 12 mm single shot

I have come to possess this gun and need some info on this gun.

In breaking it down the fore grip and barrel have the same "116 JP" engraved on them. Due to rough condition and heavy wear I haven't found anything on the stock or the receiver yet.

Can someone point me in the right direction or provide your knowledge.

It is a single shot 410ga and 12mm.

I'm told the 12mm is 44-40 cal? Is that correct?

There is a date on the barrel of August 12, 1913.

Thanks

12mm is .472. A quick google turned up nada for 12 mm cartridge. 44 is 429, 45 is 452 and 45-70 is 458. That's all I got

12mm is .410 aka 67 gauge.

Just found this regarding the whole 410 44-40 issue.
http://www.fourten.org.uk/mwpre410.html

Seems yes it can be done?

Good story.

I enjoyed it also. Thanks for posting

I had one of those when I was a youth. Also it would only shoot the 2.5" 410 shells.