AR SBR Question


June 18, 2011, 12:16 PM
I understand that the lower is the firearm, so is it legal to use a single lower with multiple short uppers so you could change between 5.56, 9mm, and .22?

Can you effectively do this with the AR platform?

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June 18, 2011, 08:56 PM
Yes, but you will need to specify which calibers you will be shooting on the NFA paperwork (under "Caliber").

Some people think you can do without (for example, just fill it in with 5.56/.223), but I've never heard if that's a good thing or a bad thing.

June 18, 2011, 09:06 PM
Yes. Used to be you could put "multiple" or something like that -- under barrel lengths and calibers. Apparently that's now not being accepted. However, putting down a list of which calibers and which barrel lengths you're planning to use (or think you might someday use) is acceptable.

Some folks have pointed out that no one seems to ever have gotten in trouble for being found to have a, for example, 7" .50 Beowulf upper installed when the Form 4 said 12" 5.56... but there doesn't seem to be a great reason to tempt fate.

June 18, 2011, 09:30 PM
Some folks have pointed out that no one seems to ever have gotten in trouble for being found to have a, for example, 7" .50 Beowulf upper installed when the Form 4 said 12" 5.56... but there doesn't seem to be a great reason to tempt fate.

Alternately, you could also worry that your gun isn't a multi-barreled firearm capable of simultaneously firing .50 Beowulf and 5.56mmm, yet your form says it uses both calibers.

Aaron Baker
June 19, 2011, 12:03 AM
Although I'm not 100% on this, I think that if you ask the ATF, they say that you only need to notify them if you make the change "permanent," meaning that you get rid of your original upper. "Temporary" changes seem to be okay.

However, I don't know that there's any part of NFA law that says they can dictate what configuration your rifle takes. You registered a short barreled rifle. It's still a short barreled rifle. Who cares what caliber it is? Just because they ask on their form doesn't make a legal requirement that it stay that caliber.

If you ask me, it's no different than adding or removing a flashlight from the rail. Accessorize your registered AR15 lower however you want.

For what it is worth, I own an SBR AR15 registered with a 5.56 barrel, but I regularly swap on a short barrel .458 SOCOM upper.


June 19, 2011, 09:16 AM
How easy is it to swap calibers? Are there components in the lower that need to be changed?

I'd be interested in a .458 or 6.8 for deer hunting.

I'm giving this thought because my weak arm has been partly disabled making full size bolt guns impracticable. I was looking online and it looks like people can shoot SBR ARs relatively well, even one handed.

I'd be doing this over time as funds permit, so I think the AR platform would be great because I could go through the registration process with a striped lower and gradually build the first configuration and then add uppers.

June 19, 2011, 09:17 AM
One other thing, I've shot ARs a couple of times, but never owned one. So I'm definitely a noob in this area. Thanks for the help.

June 19, 2011, 09:28 AM
There are a whole range of calibers which will work, or which have been specifically designed to work, in the AR-15's mag-well. .204 Ruger, .243 WSSM, 6.5 Grendel, 6.8 Remington SPC, .30 Remington AR, .300 Blackout, .300 Whisper, 7.62x39mm, .450 Bushmaster, .458 Socom, .50 Beowulf -- and more.

As far as the lower goes, no modification should be required, although with some of the more powerful rounds you might want to choose your butt-stock carefully, as some of the lighter collapsible stocks can be damaged by the slightly increased recoil.

Where the real problems crop up is making the magazines work. Some (ok., most) of those rounds require special magazines to function. Some, like the 7.62x39 are too tapered to work really optimally in the AR-15's straight mag well and making the gun reliable takes a lot of tinkering, but most of those in that list are optimized to function very well, with the right mag body, spring, and follower.

So, long-and-short of it, you can have one lower and swap between several different uppers (and the right mags to go with that cartridge) very easily.

June 21, 2011, 01:20 PM
Aaron is correct that you only need to notify the ATF if the 'permanent' configuration of the SBR changes. A simple note to them with a copy of the Form 1/4 will suffice. You can have as many short-barreled uppers for your SBR as you (and your bank account) desire. BUT...if you have additional ARs, be aware that ATF can consider that 'constructive possession' if they are stored together. I leave the upper that was described on the Form on the SBR except when I want to shoot something else; then I go back to the Form configuration when I am done.

Aaron Baker
June 21, 2011, 09:11 PM
MasterSergeantA isn't wrong about constructive possession, but I think people worry about it a little too much.

First, just to clarify, since people often get this confused: constructive possession is a legal term meaning that you possess something that you don't actually have in your hand. Constructive, in this instance, is a legal term that is the opposite of "actual." Where people sometimes get confused is in thinking that it has anything to do with "constructing" a short-barreled rifle or a machine gun. It doesn't. A good example of another type of constructive possession might help illustrate this.

If you have a baggie of cocaine in your hand, that's actual possession. If you have a baggie of cocaine under your driver's seat, and you're in the car, that's constructive possession. You don't "actually" possess it, but you legally do.

So if you have a non-registered AR15 lower receiver, and you put a short-barreled upper on it, then that's ACTUAL possession. But if you have a non-registered AR15 lower receiver and a short-barreled upper sitting in an otherwise empty gun safe, but they're not assembled together, that's CONSTRUCTIVE possession of an illegal short-barreled rifle.

Where it gets fuzzy is that all AR15 uppers and lowers are theoretically interchangeable. So if you have one SBR-registered lower receiver and one regular ole AR15 lower receiver, and you have a variety of uppers for both, some folks get concerned that the ATF will come along and say, "AHA! You could assemble both your lowers as SBRs, but only one is registered! You're going to jail!"

Here's my opinion, though: don't worry about it.

First of all, there has to be a reason for the ATF to be looking at you. If you're a regular person who doesn't get into any sort of criminal trouble on a regular basis, the ATF isn't ever going to be peering inside your gun safe. They just aren't allowed to come inspect your home without a warrant, and they have bigger fish to fry anyway. (If you're a interstate cocaine trafficker, you might be at risk, but you probably don't register your SBRs anyway.)

Second, I think the only situation that a decent criminal defense attorney couldn't get you out of is one where you've actually assembled an illegal SBR (short upper on a non-registered lower) and that's ACTUAL possession, not constructive possession anyway. Or... if you had only a non-registered lower, and had a variety of both short and long barrel uppers sitting in the gun safe with it. Then they would (perhaps rightfully) ask "Why have a short barrel upper if you don't have a registered lower? You're clearly planning to assemble them together, illegally, some day even if they aren't assembled right now." THAT is constructive possession in a nutshell.

But if you have unassembled AR15s of both the registered and unregistered variety with both short and long barrels available, logic does not dictate that you will eventually assemble an illegal weapon. If there's a way to do it legally, then "innocent until proven guilty" protects you by logically assuming that you're only going to assemble them as legal firearms.

In short, as long as the parts you own can be assembled into a legal configuration, rather than ONLY being able to be assembled into an illegal configuration, I wouldn't go worrying about constructive possession.


Zak Smith
June 22, 2011, 02:16 AM
You cannot possess extra SBR uppers if you possess any non-SBR/pistol lowers. That's not legal advice-- it's what the ATF says.

June 22, 2011, 02:41 AM
I started to post my opinion as an LEO in my state but Zak's post caused me to wonder if I'm not missing some vital information...

Aaron Baker
June 22, 2011, 11:11 AM
Zak, I don't think you're wrong, but I'd like to see a source.

The ATF says a lot of things, and that doesn't make it law. What it makes it is the opinion of the people who are charged with enforcing the law. So if they say that you better not have extra SBR uppers if you own ANY non-SBR lowers, then that means they might prosecute you if you don't comply. That doesn't mean you'd lose, but fighting court battles is expensive, so do so at your own risk.

But from the brief research I've done, the ATF's position isn't consistent on this. Some ATF agents that folks have spoken to have said it's okay to have extra short uppers and also own regular AR15s, as long as you have 16"+ uppers on the regular AR15s.

Also, as I said before, you'd have to have a reason to be under the scrutiny of law enforcement in the first place before someone is standing around trying to interpret the contents of your gun safe.

I think we can all agree that if you have 2 short uppers, 1 SBR lower and one regular lower, but no 16"+ uppers, then you'd be in trouble, since there's a fairly obvious intent to construct a regular lower with a short upper.

But if you're more like the regular AR15 collector, who has 2 short uppers, 1 SBR lower, 4 regular lowers and 8 16"+ uppers, then I find it hard to believe that the ATF could get a conviction on the basis of "constructive possession."

This last example is similar to the Thompson Contender case, which the ATF lost at the Supreme Court level. The ATF would like you to believe that the ruling in Thompson Contender is limited to the facts of that case specifically, but the Supreme Court and lower courts would likely disagree. If you have a collection of parts, and those parts can be assembled into a set of legal configurations (with no receivers left over), then you can't be assumed to have the intent for constructive possession. But if your collection of parts can't be assembled into completed rifles without ending up with an illegal configuration, then you're probably in trouble.

This is my conclusion: if you are going to possess multiple short barrel uppers for your registered SBR lower receiver, then you should only own non-registered lower receivers if you have a 16"+ upper for each one, preferably already installed on it.

I will add this warning: this is MY opinion, and the ATF may disagree with my opinion. That doesn't make them legally right, but you may have to fight an expensive, lengthy court battle if you are caught following my opinion instead of the ATF's. I am a lawyer, but I am not your lawyer, so this isn't legal advice and I'm not going to represent you for free if you get caught. So take that for what it is worth.

(who is frustrated by the tyranny of the ATF's non-legally-binding "opinions")

Zak Smith
June 22, 2011, 12:35 PM

4. Can you have several short barrel uppers (less than 16 inches) for the registered AR and still own semi-auto AR's?

The definition of a firearm in section 5845 of the NFA includes a rifle having a barrel or barrels of less than 16 inches in length. An individual possessing more than one short (less than 16 inches) barreled upper receiver for a registered AR15 machinegun along with one or more semiautomatic AR15 rifles would have under their possession of control an unregistered short barreled rifle, a violation of the NFA.
If you want to talk about "oughts" and "shoulds", then it's a question of legal strategy to get the law changed. If you are interested in compliance with the law as its regulatory agency interprets it, you need to do the research and do what it says. I was able to find this cite in less than 5 minutes with Google.

Making up "your own" interpretation is like ignoring you're pregnant-- you're going to get a surprise.

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