Form 1 SBR questions

[thedave1164]

So I am considering doing a form 1 on one of my lowers, it is currently marked as multi caliber, my understanding is the it has to be marked with a specific caliber such as 5.56, would I be able to shoot a 300 BLK upper on it after it was approved?

I guess the biggest question really is, can I swap uppers of different length and caliber on the lower after it is SBR'd?

I know I can't take it out of state without notifying the ATF

TIA

[kidicarus13]

Changing Your SBR Upper with a Different Caliber Than the Registered Lower - National Gun Trusts

https://www.nationalguntrusts.com/blogs/nfa-gun-trust-atf-information-database-blog/changing-your-sbr-upper-with-a-different-caliber-than-the-registered-lower?srsltid=AfmBOopKm-A83ugVxjx9hX-zPrEwu7OY6FIMYpLHqvCTYuoAL8qlLO93

[Oscar77]

FPNI

[thedave1164]

thanks for the link, now I know what is involved.