SIGforum
Form 1 SBR caliber question

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/380105858/m/8560072315

January 24, 2025, 11:11 AM
ElToro
Form 1 SBR caliber question
If my lower says “multi” but my form 1 stamp says 5.56, can I put a 300 upper on it ? Or am I stuck with 5.56 upper only ? Should I have entered multi on the form 1 ? Or should I just make another SBR slower to be safe.
January 24, 2025, 03:10 PM
Dwill104
They won’t accept “multi” any more, even if it says it on the lower. You have to specify a caliber. After it’s approved, you can change to uppers of different calibers. It’s recommended that you retain an upper with the registered caliber.
January 24, 2025, 04:44 PM
hrcjon
Dwill104 is as usual correct. If you don't want to retain the upper that put the SBR in the configuration that it was built you can notify the ATF of a new configuration that you do retain.


“So in war, the way is to avoid what is strong, and strike at what is weak.”
January 24, 2025, 05:08 PM
ElToro
cool thanks guys. It's registered as 11.5 inch. I have several 11.5 uppers as well as 10.5 and 12.5. all 5.56 but not planning to get rid of any. just concerned about the issue of my lower saying "multi" and my file tax stamp saying 5.56. but if it not changeable then so be it.

I found a 9 inch 300 blackout including BCG for $200. I just want to stay perfectly legal.
January 24, 2025, 09:27 PM
hrcjon
the only things that matter on your lower at this point are your name, city and state and the serial number. everything else at this point is completely meaningless.


“So in war, the way is to avoid what is strong, and strike at what is weak.”