I've had a TM1 Thompson Carbine by Khar since 2016 and I only recently sent in a Form 1 to SBR it. The Form 1 is approved, but I still haven't gotten a barrel for it yet or figured out who I want to help with the barrel swap. I just had a quick question as to what barrels are compatible with it or which ones would be the best for an accurate Thompson M1A1 reproduction? I also thought I heard that Khar changed the threads on their barrels so that they will not work with USGI barrels. Is there a difference between a barrel for a semi-auto Thompson vs. a full-auto Thompson? Any help would be appreciated.