One of the few guns exempt from the NFA for having a shoulder attachd to a pistol;
Not entirely, unless the ATF has changed their mind, AGAIN...
It's sort of exempt as a curio & relic.
I had one, a Bolo, rebored to 9mm. When the ATF decided it was exempt from NFA registration due to Curio & Relic status, I got the stock/holster. Had it for a decade + and THEN the ATF changed its mind, (refined the definition according to them) and stated it was only exempt if the stock was also a an original, a modern reproduction was not allowed other than as an NFA item.
There are no numbers on the stock wood or metal, there is nothing to positively verify the stock is original or reproduction other than general appearance. My (I assumed) reproduction stock didn't look new, it looked decades old at the least. However, with no way to prove it, one way or the other I sold the stock, and then some years later, sold the pistol.
I MIGHT have been able to convince a court that it was original, and just exceptionally well preserved, but couldn't count on it. SO I avoided the risk.
And yes, its a barking stupid law, especially when the identical item made in 1920 is legal and the exact same thing made in 1950 is not.
Nice Broomhandle. still in .30 Mauser??
And yes, the hammer rings will roughly date the model, for a few years the rings were raised and protruded out from the hammer. These are called "cone hammers" though I'd have to do some research to tell you what version was made when.