We all wish the laws and regulations were simple, direct and clear. That's not going to happen.
Originally Posted by 1biggun
Remember that a letter from the BATFE binds them, if at all, only in favor of the addressee.
There should not be any confusion about this. The BATFE includes "muzzle attachments" (not muzzle DEVICES [check the sticky in this forum for confirmation if you need to]) as a countable part without regard to the function or lack of function. Therefore, if it attaches near the muzzle, you should consider it a muzzle attachment and count it.
Should you need further "proof" the AES-10 Bs that were equipped with a muzzle nut had them tack welded (thus making them part of the barrel). If it was not a countable part it would not have had to be welded.