individual owner of NFA can ship via tax paid form 4 direct to a dealer in buyers state, no need for dealer in sellers state, but still 2 form 4 tax paid transfers.
C&R collector can buy C&R NFA items direct from seller in another state 1 form 4 tax paid transfer.
FFL can buy NFA direct from out of state any NFA item form 4 1 transfer.
FFL with SOT can buy NFA on form 3 no tax from FFL SOT out of state.
Anyone can buy direct from Govment agency in/out no tax form 5