SBR caliber

[greg1147]

If I have a SBR registered as multi caliber can one put a 300 BLACK OUT upper receiver on it as long as the barrel length is the same or longer.
Asking for a friend

 

[hafejd30]

To my knowledge you can swap uppers at will pending you always have the original registered configuration on hand. If you change permanently they ask you update the ATF

 

[Deepwoods]

To my knowledge you can swap uppers at will pending you always have the original registered configuration on hand. If you change permanently they ask you update the ATF

I *think* that you can write the ATF and inform them of configurations that differ from what the original form states. What I recall was that you are informing the ATF, not seeking permission for these additional configurations. (obviously, the additional configurations have to also be legal.)

 

[AMMOWASTER]

There's no length restrictions and you don't have to keep the original stuff on hand. The wording is something along the lines of being able to switch it back which on an AR is easy. Most of this stuff was written long ago before it was common to swap stuff around.