I did a Form 1 and made an SBR when I lived in the Dakotas. I moved to Michigan years ago and before SBRs were legal in this state. As such, I had to install a 16" barrel and sell the short one in order to bring it into Michigan, all of which I did. I also wrote a letter to the AFT Notifying them of the change. They replied and indicated they updated their registry and since the rifle no longer fell under the purview of the NFA, I could bring it to MI without violating state law. I saved the letter with my original Form 1, which I still have. My question is, now that SBRs are legal in MI, can I covert it back by sending another letter to the ATF notifying them of the change, or do I need to do another Form 1 and get a new stamp? I plan on calling the NFA branch and asking them, but I am looking for info on the issue before I do.
Thanks