I have two registerd AR receivers (registered as SBRs)  One in 12.5" and one in 10.5".  Recently sent off both to be cerekoted.  The 12.5" one came back already.  The 10.5" has some old bad engraving, and the smith is having to do a littl extra to fill before cerekoting which will take a couple more weeks.  

My problem is I just got back my 10.5" upper from ADCO after intalling the AA Piston Retrofit Kit.  I am itchin' to try it out.

So, I was wondering if it would be legal and acceptable on my next range trip to slap the 10.5" upper on my 12.5" registered lower, temporarily, to test fire and sight in the Aimpoint Micro on it. I'd still bring my 12.5" upper because I want to shoot it too and to prove that the 10.5" upper isn't permanent.

Under Section H on my Form 1 for my 12.5" I put "Additional Barrel 11.5"  I hope that wouldn't restrict me to 11.5" only, temporarily.  

Well? Advice?  I don't want to do anything illegal or cause nay problems.  If there's a chance it could be an issue, I'd rather not.

Thanks in advance.

lock this thread....never happened ........ that is all........

totally legal

+1
The fact you dont have your registered lowers in your possession is a big time no no. Delete this and get your lowers back pronto and never speak a word of this again

I'm not sure why they are saying to lock it. Unless I missed something? Which maybe I did. But you have have an SBR lower that you want to run two different uppers on. That's fine. There is nothing wrong with that. I've got a couple of uppers I run on mine. I run a 9mm, .223, 5.45, and .22LR upper on it.

He does. He has two lowers. The one that he had his 10.5" on isn't back yet. He wants to run both of his uppers on the one lower that did make it back.

I think the concern was over the fact that he sent out two registered lowers to have work done on them.  

I will assume the OP followed the advise of the ATF, quoted from their web site below.

February 18, 2000

Repair of NFA Firearms
The National Firearms Act (NFA) Branch has received numerous questions concerning the repair of NFA firearms.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) does not consider the temporary conveyance of an NFA firearm to a gunsmith for repair to be a "transfer" under the terms of the NFA. Thus, an ATF Form 5 application is not required.

PLEASE BE AWARE THAT OTHER DISPOSITIONS, SUCH AS DEMONSTRATION OR SALE, ARE TRANSFERS AS DEFINED IN THE NFA AND MUST BE COVERED BY AN APPROVED APPLICATION TO TRANSFER AND REGISTER. TRANSFERS WITHOUT APPROVAL ARE VIOLATIONS OF FEDERAL LAW. ANY FIREARM INVOLVED IS SUBJECT TO SEIZURE AND FORFEITURE AND THE PARTIES TO THE TRANSFER ARE SUBJECT TO CRIMINAL PENALTIES OF UP TO 10 YEARS IMPRISONMENT.

In order to avoid any appearance that a transfer has taken place, ATF strongly recommends that a Form 5 application be submitted for approval prior to conveying the firearm for repair. ATF believes this will provide protection to the parties involved as it will document the repair of the firearm and help ensure that a "transfer" did not take place. In addition, an approved Form 5 will assist Federal firearms licensees in establishing that their possession of the firearm is lawful. However, if no Form 5 application is used, ATF recommends that both parties document what type of repair is being performed. This may be done via work or repair order or other similar documentation.

Accordingly, Item I5 in the "Questions and Answers" section of ATF Federal Firearms Regulations Reference Guide 2005 (9/05), suggests that the owner obtain permission for the "transfer" of the NFA firearm by submitting a Form 5 application and that the gunsmith do the same for the return of the firearm.

Federal firearms licensees must record the acquisition and disposition of the firearm as required by Part 479, Title 27, Code of Federal Regulations.

I think some of the comments above are related to sending the lowers out for repair work.  You are allowed to send NFA items out for repair to a licensed FFL for repair, so as long as your smith is an FFL holder there is no need to do a form 5.  Years ago ATF said all repairs had to be done on a form 5 this is no longer the case.  I generally only let gunsmiths work on my NFA stuff if they also have an SOT, there is no legal reason for this, but I just feel more comfortable that they know the rules a little better than an 01.

ETA: Beat DSB by 2 seconds, plus he has citations, I will put myself in the corner.

I sent the receivers for refinishing work to an FFL/SOT gunsmith (and included copies of my paperwork).  The FFL/SOT is aware that the receivers are registered short barrel rifles.  The FFL/SOT gunsmith said that he services NFA items and that this method was OK.  There is no doubt that there is no transfer and only refinishing considering the previous work on the other receiver, the bill for the service, and the long string of e-mails.   Although, I do thank everyone for their opinion and insight on the proper process to send a NFA item for service.