From Silencer Shop:
One question that has always been a mainstay in our most-questions-asked category is whether a specific silencer will fit a specific gun. With threading looking similar, and acronyms being thrown around like hot tamales, we understand your plight. As the suppressor industry grows, it seems thread pitch options have too.
While some thread pitches are more popular than others due to military use or it being made common by specific firearm manufacturers, the last thing you want to happen is to finally get your suppressor in and realize that it doesn’t match up with your host firearm’s threading.
The list that we are providing you is to serve as a reference for quickly locating how your barrel may be threaded. Remember that factory barrel threadings and after market threadings aren’t always the same.
Details, which are kept up to date, are here.
Interesting to see significant variation in thread diameter.
This sort of stuff suggests it’s worth while putting a dial caliper or micrometer, and a thread gauge, to work to double-check the answers.
Very few put in the industry put their heads together on that one. At the shop it was a major pain in the ass keeping up with all the different suppressor adaptors. Like Pkoning and the post said. trust but verify.
I suppose I shouldn’t be surprised. I have a box of Brownells gun screws in all sorts of oddball sizes and threads. I suppose some of these date back to Sam Colt himself, long before the national thread standard.
Of course, guns are not the only places where you find bizarre threads. Two of my favorites: 16C collets (for lathe work) which have an internal thread 1 11/16-20TPI, and an external thread M47.5-1.75 — yes, inches and metric mixed. Or the DIN (that’s a German standard) microscope lens thread, 0.7965″-36 whitworth.
Barrel threads (barrel to receiver) seem to be all over the map too, if I remember right. Don’t some of them use square thread? That’s actually a rather bad choice.
I find it interesting that I can’t buy 1/2″ x 28 taps and dies off-the-shelf here in Oz.
They aren’t restricted by law as far as I can tell, as it’s OK to have them made, but expensive.