I know that barrel lengths can change as long as it's not permanent, is it the same for caliber?

Looking at changing from 5.56 to a pistol caliber.  I've converted a AR to 9mm many years ago but would like to try it again but with a SBR.

You can change either any time, for any SBR, and you don't even have to notify anyone.

For ARs, both are considered temporary changes and ATF really doesn't want any notification.

If you're going to sell it later without the setup it's papered as, then it would be wise to send notification of the reconfiguration and forward a copy of the acknowledgment with your transfer form, to show why the data is different.

Your Form 1 is merely a request/approval to initially manufacture an SBR in the configuration outlined on the Form 1; once that has been accomplished (technically speaking) you're free to reconfigure as you'd like.

Ok, very nice!  Thank you gents for the info.

wyoshooter12

No shit?

I’m back and forth on which caliber to go with my next SBR.  I want to do it as .300blk but I’m not completely sold on that caliber like I am 5.56.  I’ve hesitated on how to proceed since I’m unsure if I’ll abandon .300blk and go back to 5.56

Your thoughts?

You can amend your Form 1 at any time before building, and you can submit a description revision to add additional configurations after approval but there is no requirement to do so.

Here is a current thread you might find interesting:

https://www.ar15.com/forums/Armory/Was-told-something-by-BATF-that-is-counter-to-what-most-here-believe-is-fact-/17-491131/

If you have the time and money, NOW is always a good time to cast a Form 1 upon the waters.  If you don't build you have 3 years from the date the tax is paid to request a refund and cancellation of an approved stamp.

Once you go black....
I shoot mine way more than .223