Is This Workable?

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.

It seems like this post references a similar issue:

https://www.m4carbine.net/showthread.php?t=22449

If not, I would highly recommend calling the ATF NFA branch at: 304.616.4500

“I don’t want to do anything illegal or cause any problems. If there’s a chance it could be an issue, I’d rather not.”

A quick phone call to them and you can be sure for your situation, and if it is not legal, they will tell you what you need to do in order to make it legal.

I called them last week on another issue and found them to be very polite, helpful, and willing to answer my odd ball question. Also, get the name of the reviewer/agent/investigator (for CYA purposes) and they will usually cite the code which determines the legality of your actions.

Good Luck! Let us know how it goes, and hope you get a chance to run your new little bad boy!

I will second getting the name of who you talked to and as much information about them you can. From first hand experience not everyone who works for the ATF knows what’s right and wrong as some laws are open to “interpretation”. Just make sure to cover yourself.

Yes, you can. Once a lower is registered as a SBR, it can have any length of upper put on; be it over or under the length on your form.

Enjoy it.

Are you sure? It is my understanding that it can be over the length, but not under. If you have an SBR with a 10.5" then you can go higher, but you cannot add a 7.5" upper.

Positive. You can change configurations and barrel lengths on an NFA item. I believe ATF likes that if it will stay in that new configuration, that you send them a letter detailing the change to the configuration. People (including myself) swap various length uppers and calibers on registered M16 lowers, with AR15 DIAS, and swap HK conversion devices into all sorts of different hosts.

If you are still unsure, go post this over on Subguns.com. There are a large number of long-time very knowledgeable FFL/SOTs that hang out there and they can certainly answer this definitively.

I ran into this with my lower that I had registered as 14.5", but then I never bought the 14.5" I planned on buying. I wanted to use a 10.5" instead that I had at the time (I now have two 11.5" uppers and that’s it).

I called BATFE, they told me to send them a letter explaining what barrel length I was changing it to. So I typed out a nice, well-written and easily understandable letter and then mailed it to them. This was about 5+ months ago. They said they would send me something to notify me of the update, but I still haven’t received anything.

But about one month after I mailed that letter to BATFE, I started using my 10.5" upper on that lower, and now I use my BCM 11.5" on it. I did my part and notified them of the change, so I know I’m covered. I honestly don’t think I’ll ever receive anything from them, but believe that they just noted the change in my “file” or directly on the Form 1.

I’m sure you’d be okay if you put the 10.5" on there, and that no one would say anything to you (no one’s ever bothered me about any NFA items anywhere), but I personally didn’t feel comfortable strapping a shorter upper on mine until after I sent BATFE my notification letter.

-Paul

Safest route, whether it’s a permanent change or a temporary/occasional change, would be to send a letter (certified with return receipt) to the NFA branch and tell them what you’re doing. Either a permanent change, or a “hey, by the way, I am adding another configuration but the permanent length is unchanged.”

Keep a copy of the letter with the certified slip and the return card (when it comes back) stapled together and tucked away wherever you keep your Form 4 or Form 1 for the gun.