So I picked up my newly engraved SBR lower (my first)at my LGS today. As I was doing this I overheard something that interested and confused me at the same time.. Guy was asking question's about SBR's, He asked if he had to file a new F1 if he mounted an upper with a barrel SHORTER than listed on the form 1 for his existing registered SBR.. The employee answered YES

I did a little research and found a few references on forums that state you can't go shorter than what's listed on the F1.. My understanding was that once you registered the SBR with say a 10.5 barrel length you could go longer or shorter and still be legal.. now I'm not so sure. I spoke with the guy at the shop and according to him this is not a "rule" but an "opinion" the ATF holds, another grey area of the NFA so to speak. He also added that he had a lawyer that does NFA trusts and ATF agent state the same.." you can go longer than listed on the form but NOT shorter".

Any truth to this? I registered my SBR with a barrel length of 10.5 since that was the upper that would be mounted 90% of the time. I have a 7.5 upper that I had PLANNED on using with this SBR lower as well.  The 7.5 is mounted to a pistol lower so no legal issue with having the upper. I plan to register another lower anyway so not really a big deal, this one will be a 7.5. I just thought that adding ANY length barrel to a registered SBR lower was GTG... maybe not?

Longer or shorter, doesn't matter...neither does caliber.

LGS employee doesn't know what they're talking about, which is (unfortunately) an all too common situation.

I would normally agree.. the guys at this gun shop are not the type to spread bullshit. I'm not saying its true, just that this is what he has been told by a NFA lawyer and ATF agent who may also be wrong. I did find some forum posts that support what he said... it's on the internet it must be true. I can't find anything in the form of a ruling or opinion from the ATF that states this.

My limited understanding agrees with you, once you build the item in the configuration listed on the F1 you can do what ever the hell you want afterwards..

It is my understanding that as long as I have the original upper I got the stamp with I could swap on whatever upper I wanted to.  Example- I did my SBR with a 10.3" barrel but also have a 7.5" I run on it and I did use a 14.5" before I pinned the FH on it.

This is what I have always heard... upper swapping and other parts swapping that would affect the barrel and OAL are kosher so long as you possess the parts to return it to the state that is listed on the form 1.

Zero requirement to be able to return to the original configuration.

This isn't necessary. A registered SBR is a registered SBR. It can have any barrel length you want it to have. The ATF politely asks that if you make any permanent changes to the configuration, you notify them in writing, but it is not a legal requirement. You can build the rifle with whatever barrel length you want, and change that at any point and sell the original barrel. It doesn't matter.

More gunstore derp.  Once the rifle has been built it can later be changed in caliber and length.  Their is no legal requirement to notify the ATF.

NFA lawyers fall under the same umbrella as dealers. Some are very good, while a lot don't know what they're talking about.

And don't agree with me...read the statutes. Ask that LGS employee, or the lawyer, to give you the statute behind their opinion. They won't be able to do it.

The ATF itself (on their FAQ) page simply says they recommend you notify them of changes...you know they'd use require if they could back it up.

Read the NFA FAQ on the ATF website.

You can even put a 16" upper on it and treat it as a non NFA item so long as you leave the SBR upper at home.

Gun store and local ATF agent are fucking wrong.

NFA lawyers fall under the same umbrella as dealers. Some are very good, while a lot don't know what they're talking about.
This is the same lawyer that did my Trust, at least he got that part right

And don't agree with me...read the statutes. Ask that LGS employee, or the lawyer, to give you the statute behind their opinion. They won't be able to do it.
I have, I thought maybe I missed something.

The ATF itself (on their FAQ) page simply says they recommend you notify them of changes...you know they'd use require if they could back it up.
Yep, I have no plans for notifying them, no changes I make will be Permanente.

So once I build my SBR I can change length and caliber.

Rifle has to state somewhere what caliber, correct? So I can't use a lower that says .223/5.56 and make a .300blk?

So if I use a lower that says "Cal: Multi", I either have to be able to see the actual caliber on the barrel or engrave it on the lower. If I engrave "Cal: 5.56" on the lower, can I not change the caliber without having the previous engraving filled in and a new engraving done with the correct caliber?

So is it best just to have a visible caliber listed on the barrel?

I trust BigWaylon over your NFA Lawyer.  

You're overthinking this. Which is what we all do when we first get into NFA stuff...which is why the people who live in this forum know so much. It's because of paranoia and research.

Every AR-15 barrel I've ever seen has the caliber engraved on it. Don't fill in any engraving!

Well I've come to find out that Radical Firearms and AR-Stoner do not list the caliber on their barrels. I'm guessing that they are both made by Radical as the only marking on either of them is an "R".

That's odd... I have 2 radical melonite barrels, both are marked with "5.56" and the twist rate, 1/9 for one, the other 1/7. Both are stamped in between the GB and FSB area on the top of the barrel. Neither have a "R".

On a side note, my lower is marked "multi" for caliber, I had just my trust info engraved... the barrel markings are perfectly acceptable for caliber identification...if they are there

When you Form 1 (make) an SBR, you are documenting the original configuration. Once it's built you can change it however you want.

There is no legal requirement to update the ATF, but as a courtesy they ask that you notify them with "permanent" modifications. Since AR's are like Legos, you could argue that nothing is really permanent.

The caliber on the lower doesn't mean anything. Plenty of calibers that use standard AR lowers rollmarked 5.56mm or .223. Nothing illegal or wrong.

Sadly people follow their advice.

Recently met a guy with registered Colt M16A1 (20 inch BBL). Wanted to put it in M4 config, LGS told him to SBR it first. He did. I thought he was pulling my leg, but he did send in an F1. Still waiting for it to come back. Better safe than sorry he says.

If this were true, everyone would be submitting Form 1s for 7" barrels and be done. It would be a very easy decision...

Gunstore idiot is an idiot

Hopefully they don't approve that and take a MG out of the registry.