BTW, some do have metric threads.
I personally haven't run into that but I'm sure you are correct sir!
I'm lucky in that there is a good friend of mine right down the road who has a black powder shop. The guy has everything on the planet related to black powder shooting. He's a complete expert on this topic and has a huge trailer he takes to supply competition shooters around the state. (Bill Hammond of Spring Brook Trading Post). Bill is the real deal.
I feel sorry for some of you guys that have to travel miles or order something form the net and can only wonder and hope it's going to work!