When I started on my SBR project last year I contacted LMT and asked them what the OAL was of a 10.5 upper(didnt buy it till last monday) on a defender lower which I already had when I submitted my form 1.
I put down what they siad 25-3/4 and never thought about it till I went to it with a measuring tape tonight and came up with 26.5 oal (aw s#@*)
3/4 more so I removed the upper after I relized it and put it away.
Now who do I notify?
From the BATFE’s FAQ page:
[i]"Changes to the Description of a Registered Firearm:
When there is a change in the configuration of or a modification to a registered firearm, the registrant should notify the NFA Branch in writing so that the NFRTR (National Firearms Registration and Transfer Record) can reflect the accurate description of the firearm."
National Firearms Act Branch
Bureau of Alcohol, Tobacco, Firearms and Explosives
244 Needy Road
Martinsburg, WV 25401
Phone: 304 616-4500
Fax: 304 616-4501
Hours: 8 a.m. to 5 p.m. Monday through Friday (except federal holidays)[/i]
Send them a letter with the correct info on your weapon and explain the required changes to its description.
Derek
tiger seven is correct. Send the letter with a copy of the approved Form 1/4. Send the letter certified so you have proof they received it and then carry on with life. Eventually they will send you some response saying thanks for the info.
Mark
I don’t think it matters. The barrel length is what will get you nuts chopped off if you’re in violation.
I’m sure I estimated my OAL since I didn’t have the weapons built until I had the forms approved.
Also, I’ve read that the OAL is supposed to be measured with the Stock in the extended position (if equiped with a car type stock) for those thinking of doing the SBR shuffle.
They actually want the stock in the shortest position. Go figure.
Mark
I’m sure these questions have been asked before:
On a form 1 for OAL could one put say 25" or less?
And will ATF actually accept “multi” as the caliber?
If these things are acceptable (they sure seem reasonable) why do anything else?
That would make more sense to me. But someone else posted the opposite. I can’t even remember what I based my estimate on… I think collapsed. 
I wouldn’t put either of those down. Just quantify the OAL somehow.
And I’d put “9mm & 5.56” (or whatever) rather than “multi”. The less ambiguity, the less likely any delays.
I agree to just put a length. Don’t put “less than…” or anything like that.
ATF changes the rules as they go a little bit. For example, they used to approve Form 1s with caliber listed as “multi” or “9mm, .22lr, 5.56” and such. At some point they said to only list a single caliber, barrel length and OAL. Same with Trusts. They used to approve Form 1/4 with only a Certification of Trust. Then at some point they demanded to see the entire Declaration AND the Schedule A.
I would suggest putting a single entry for length, OAL and caliber. Once you get your approved Form send a copy of the Form with a letter explaining all changes (e.g. additional calibers, barrel lengths and OALs). Send this certified and keep a copy of the receipt showing delivery.
Mark
So if I have a SBR in 6.8 with a 12.5 barrel but I also want to have a 5.56 with a 10.5 barrel I submit on the 6.8 then send a letter saying I will also be using a different upper in 5.56 with a OAL of … ?
I don’t know what they’d say if you sent a letter that you planned to use a barrel shorter than what is stated on the original F1.
I don’t know what they’d say if you sent a letter that you planned to use a barrel shorter than what is stated on the original F1.
At least as of a few months ago they send you a letter basically saying “Thanks for letting us know.”
FWIW, my dealer had me submit the length with the stock extended, as well as with the flash hider removed, since, according to his logic, the ATF doesn’t consider the flash hider part of the length on a non-NFA barrel unless it is permanently attached, so it shouldn’t be considered for an NFA barrel either. It is a crazy and all too confusing world, that’s for sure.
I’m pretty sure most people estimate the OAL (I did) unless they’re buying a complete SBR. The barrel length is the important part anyway, and as stated above, you don’t need permission to change it, the ATF just wants you to notify them.
Did you measure to the end of the barrel, or end of the flash hider 
flash hider (thats the extra 3/4) to end of stock.
If I remember it correctly, if the OAL you report is shorter than the resulting OAL, it shouldn’t matter as long as the barrel length is correct. If it was the other way around then I’d be concerned.
I recommend calling them as getting the information first-hand.