I didn't go any deeper into the issue than what I could get from perusing various NFA fora, but one thing I saw mentioned repeatedly, is that in the case of the cans you can buy that accept different end caps, the can manufacturers have a letter from the ATF that says the adapters they make for that specific model of can, are not suppressor parts in and of themselves. The distinction I saw being made, was based on whether said end cap/adapter also functioned to hold the internals in. If it did, then the end cap was treated as a suppressor part, and having more of them than you had approved suppressors was double plus ungood.HTRN wrote: Bullshit. Bowers does a huge oversized thread in the back of their cans, which you then can use various adapter bushings tit to individual guns.
Internal parts are another matter.
Take that for what it is worth... I don't claim to be an authority, that was just what I found when I looked into it at those other places.