I’m just not sure that’ll fly. You have to register a firearm, not a part. With a sear, the part is the MG. But I don’t think they’ll treat the Vector the same.Yeah I was thinking of engraving a serial number on the upper. If it was registered in say 9mm and you switched between that and .45 it should be ok..? You're not permanately changing the caliber. This seems similar to a registered sear.
Yes...but that’s the problem. You have to swap the lower to change calibers.The serialized part is considered the firearm. In the case of the vector that would be the lower.
ETA... does the vector allow you to swap calibers (I was unaware of this if it can)? If so, that wouldn’t be a problem with a registered lower.