What if a registered SBRs overall length changed permanently from what was listed on the original Form 1 paperwork that was approved?

For instance, one put 27" for overall length and the more correct length was 30" when submitting the form.

Would one need to notify the ATF or is it a non issue?

Asking for a friend?!?

Not required but you can notify them if you want.  There's no official form for it, you'd just type up a letter essentially.

Non issue

If the length doesn’t matter why do they ask? Historical document significance?

how do you guys know you don’t have to notify anyone about changing the barrel length?

If I remember right the wording says something to the effect of notify them if the overall length is PERMANANTLY altered. Changing barrels, uppers, stocks etc doesn't permanently alter anything. It can be changed again or reverted to the original length. Ask my wallet for clarification

Because there is nothing in the law that makes it illegal

So it is legal to register it as a 14.5 and make it into a 10.5 and never have the 14.5 upper?

Yes, as long as when it gets into a permanent configuration, it's a 14.5

Once registered as an SBR you are free to use any barrel length you want (short or otherwise). You can throw a 16" on it and travel across state lines. You can throw an 8" .300BO on it. Doesn't matter. The point is that you haven't PERMANANTLY altered it from the registered length & caliber.  You're fine

Sorry if this has already been asked but say you file with Silencer Shop and you do all the stuff and the E-form is accepted, can you go ahead and put a stock on it immediately or do you have to wait till it goes all the way through?

TIA

Not until you have your tax stamp.

As long as it can be returned to the registered congfig

The definition of permanent must be argued by layered often.  Pull two pins and put another upper on and it is back to registered length.  Weld the barrel to the upper and the upper to the lower and you could still cut the welds and attach another one.  Sounds like the length doesn’t matter on the real world and worrying about it is akin to ‘you’d really have to piss them off to make it an issue.’

It's still not going to be an issue since there is no law against changing the barrel length.

Well, just to add to the fuckery....this is straight from the ATF's website:

"Once the firearm is registered as a short-barreled rifle (SBR) can I remove/change the “stabilizing brace” or attach an item marketed as a stock? If so, am I required to notify ATF in advance?

Yes, once the firearm is registered as an SBR, you can change out the “brace” device or stock for a different brace or stock. You do not need to contact ATF/NFA because changing the brace/stock does not change the configuration of the SBR. However, if the length of the firearm has changed you will need to notify the NFA Division."

(https://www.atf.gov/firearms/qa/once-firearm-registered-short-barreled-rifle-sbr-can-i-removechange-%E2%80%9Cstabilizing-brace%E2%80%9D)

This is some new shit that was never on their site before all this crap with the braces.

You can look up the laws concerning changing the uppers, barrel lengths, and even calibers and nothing says anything about a need to notify.  The only restriction is on caliber, you can't exceed 1/2" diameter (.50 cal) as it would then be considered a "destructive device" (18 U.S.C. § 921(a)(4): DESTRUCTIVE DEVICE, 26 U.S.C. § 5845(f)(2): DESTRUCTIVE DEVICE) (Firearm having a bore of more than one-half inch in diameter).

However with that said, you can no longer designate "Multi Cal" on form 1's.  You have to specify the caliber.  Although there is nothing that I am aware of, or can find, on the ATF's site that specifically addresses notification when changing calibers or adding new uppers in different calibers, or even barrel lengths, this COULD BE a means for them to shoot your dog if you put a different caliber upper on your registered lower and don't let them know.  Far fetched, most likely, but then again, a lot of the shit they do is vague in many respects and leaves open a broad door to screw you if they really want to.  This is common with them and done intentionally.  If they really wanted everything to be cut and dried (i.e. easy to follow, and easy to understand), they would make it that way, but they don't, thus the hundreds, if not thousands, of questions concerning form 1's, SBR's and the like on all the gun forums.

Law sites that deal with NFA will recommend that you send them a nice letter letting them know of the different uppers and calibers you intend to attach to your registered SBR lower and they specifically say to tell them you are "amending" your registration, do not tell them you are "changing" it.  Once sent, you do not need to wait for any approvals from the ATF (none will be coming).  The general consensus, however, is that no letter is required, only that the ATF requests you let them know.  

So, if you sent in a form 1 (taxed with stamp, or the freebie one (you won't actually get a stamp, only an approval form)), then have at it.  Change it around, put on different uppers, change calibers, add a stock, it's an SBR.  If you really want to send them a letter, then do that if you want, but there doesn't appear to be any law or actual legal requirement to do so.