How to (Legally) Build A Short Barrel Rifle

As defensive weapons, rifles rock. They’re easy to shoot accurately unless you’re into torching off .577 Nitro Express cigar cartridges. With box magazine designs like the those of the AR-whatever families, capacity is great, and reloading is easy. In fact, the only real downside of a rifle as compared to a pistol is maneuverability and portability.

The Skinny on the SBR

Enter the short barrel rifle, or SBR as we’ll say from here on out because we care about saving the electrons. With its compact size, an SBR can be plenty handy for a car or home use. An SBR has most of the benefits of its larger counterpart, minus a bit of velocity, but with half the calories.

The problem is that SBRs are a royal pain in the butt to understand from a legal perspective. With the passage of the 1934 National Firearms Act (NFA), they are restricted items. To make, buy, and own one, you’ll need special permission from Uncle Sam by completing and submitting a Form 1, and you’ll need to purchase a colorful and ornamentally pleasing tax stamp that will cost you $200.

Want an SBR of your very own? Never fear, we’re here to make the process easy for you.

Disclaimer

I’m not a lawyer, and I don’t play one on TV. Besides, if I were going to play something on TV, I would be a skydiving Kingsman in a Zombie movie, not some guy who sucks the fun out of everything wholesome and good.

Anyway, the law that governs the short barrel rifle market was written in 1934, before the invention of electric guitars, ballpoint pens, and Tupperware parties (yes, look it up.) As a result, the ATF has to do all sorts of weird legal interpretation as the law didn’t account for the myriad of firearms options we have today. Simply put, the law has no provision for modular systems like the AR-15 that can be built into rifles or pistols and have practical attachments like chainsaws.

Navigating this process, we’re faced with the original NFA law and subsequent laws, which are comprised of billions of pages of pages of gibberish dictated by inebriated politicians. Then there are policies issued by organizations like the BATFE that are charged with enforcing the law. Finally, there are opinion letters which are issued by said agencies to try to help us mere mortals understand how they interpret the law according to… their opinion.

While we’re going to try our very best to point you in the right direction, it’s up to you to understand and obey the law. Just be aware that if you get in trouble, waving an opinion letter on the Supreme Court steps may not help you much if you get charged with a crime by someone with a different opinion. That’s my opinion, and I’m sticking to it.

What’s an SBR?

Before we get into this, it’s important to understand what an SBR is according to the definitions that the ATF uses, so let’s make a quick diversion on that topic. In the Code of Federal Regulations, Title 27: Alcohol, Tobacco Products and Firearms, Part 479—Machine Guns, Destructive Devices, and Certain Other Firearms, Subpart B—Definitions, §479.11 Meaning of terms, we find the following:

Firearm… (c) a rifle having a barrel or barrels of less than 16 inches in length; (d) a weapon made from a rifle if such weapon as modified has an overall length of less than 26 inches or a barrel or barrels of less than 16 inches in length;

More Definitions

Given that, you need to know what the law considers to be a rifle and pistol. From the same code, here ya go:

Rifle. A weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed cartridge to fire only a single projectile through a rifled bore for each single pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed cartridge.

Pistol. A weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having (a) a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s); and (b) a short stock designed to be gripped by one hand and at an angle to and extending below the line of the bore(s).

Boiling down all the legalese, the big deal between rifles and pistols is the stock. A stock on a pistol is “at an angle… below the line of the bore” and designed to be fired with one hand. A rifle is designed to be fired from the shoulder. This becomes important, so stay with me for a bit.

What are your options to “create” an SBR?

So how can you get from zero to having an SBR? There are plenty of ways. I count three. Now that we’re all NFA law experts let’s take a look at each scenario.

Start with a rifle

If you buy a rifle and later want to convert it to an SBR, you can do that. If you refer back to the definition text, you’ll see that the law was written with this in mind. Originally it was created to discourage people from chopping stocks and barrels off rifles to make little baby rifles. You’ve always been able to do this legally; you just had to file the Form 1, pay $200, and not start any of the building processes until you get your tax stamp returned from the ATF. So, modifying a rifle into a short-barreled rifle has never been illegal, it’s just been regulated.

If you buy a rifle and want to convert it to a pistol, that’s also something that would require a tax stamp. Since pistols aren’t required to have tax stamps under the National Firearms Act, that doesn’t make much sense. It can become a modified rifle, or SBR, with a tax stamp. If you want to make a pistol per the legal definition, you’re better off just starting with a pistol rather than trying to convert a rifle into one.

Start with a pistol

You can convert a pistol to a short barrel rifle. Unless you live in one of the Republiks, pistols are not regulated. If you meet the legal qualifications for handgun ownership and can pass a NICS background check, you can get one. However, the minute you start the process of converting a pistol to a short barrel rifle, you wade right smack into the National Firearms Act and need to file paperwork and write checks. The process requires the ATF Form 1 submission, approval, and a $200 tax.

Perks of Starting with a Pistol

Starting with a pistol can be a great idea because the government is slow. Right now, it’s taking somewhere over 250 days for someone to process your Form 1 and cash your check. Maybe those artsy tax stamps are individually hand painted by Keebler elves? Whatever the reason, you’re going to have to wait a long time before you can convert your pistol into an SBR so you might as well get some use from it.

If you have a functional pistol, you can start acquiring the parts for your rifle, just don’t install any of them until you get your tax stamp. To be clear, there’s a potential gotcha here. It’s important to have the functioning pistol if you intend to start acquiring the parts for an SBR. If you have all the parts required for an SBR but don’t have parts to make a pistol, some ornery fed might assume that you have an unregistered SBR and that you just keep it disassembled. You won’t be able to prove that you’re using it as a pistol in the meantime if you don’t have any of the pistol parts on hand.

One more thing. If you start with a pistol, you can legally convert it to a rifle at any time you like with no paperwork or tax stamps. Pistols are legal, and rifles with 16-inch barrels and overall length of 26 inches are legal, so there’s no problem converting your pistol to a rifle.

Start with a receiver and parts

You can buy a lower receiver and make it into anything you want, provided you get the tax stamp first if you intend to build an SBR from the ground up. Don’t go off and buy all the SBR parts and stick them in a drawer until your tax stamp comes in. Just having all the gear to make an SBR before your application is approved can run you afoul of the law as we just discussed.

There’s one more thing to know regardless of which method you choose. You’ll need to have your receiver engraved with your name or the name of your trust and your city and state. Since you are “manufacturing” a firearm, you need to do like the big boys and stamp your identification.

Bag all the confusion and use a “fake” SBR

If you want something that has some rifle attributes but is smaller, and you don’t want to mess with any of the three scenarios we just discussed, you can just build or buy a rifle-caliber pistol. Unless you’ve been in a 24-hour news cycle induced coma the past couple of years, you’ve probably heard about pistol braces.

These devices were originally invented to help people shoot an AR-15 safely and effectively using one hand. Whether from amputation or injury, there are lots of folks who would want to do this, and the solution is pretty nifty. A pistol buffer tube has a rubber or plastic attachment that either wraps around the firing hand forearm or at a minimum, braces it, to help stabilize what is otherwise a heavy and unwieldy pistol.

Brace Yourself

Since you can rest just about anything against your shoulder, people quickly figured out that these braces make a reasonable substitute for a very short stock. Since the whole thing is a pistol, there’s no NFA process required. People who collect paychecks from the Treasury Department also figured this out and started to issue opinions on the matter.

First, they said, “No problem. As long as you don’t modify the pistol support from its original factory configuration, it’s not an SBR.” Later they said, “Hey wait a tic. If you hold this to your shoulder, you’ve modified the gun, and it’s now an SBR.” As of this writing, we’re in somewhat of a holding pattern. The ATF hasn’t sent anyone to jail for holding one of these to their shoulder, but it also seems like they’ve reserved the right to do so if they feel so inclined.

Whether you choose to use one of these pistol brace systems in a non-conventional way is up to you. There’s nothing with the word “law” behind it that’s clear on the matter, just a bunch of opinion letters, so you’re operating entirely at your own risk. User beware.

Here’s what I’m doing

I’ve got a C.O.P. integrated upper receiver and handguard from Aero Precision with a 7.5-inch barrel sitting on a shelf. While I might prefer a 10.5-inch barrel for 300 Blackout, it would be a shame not to give this one some tender loving care, right? So, the goal is to make this into a super-handy SBR, maybe even with a compact suppressor at some point.

Tips for Building

Given all the legal mumbo-jumbo we’ve just been through, what’s the best way to approach this build project? My patience isn’t nearly as boundless as the ATF’s turnaround time to issue tax stamps. Can I wait over 6,000 hours before even starting to gather and assemble parts for a nifty 300 Blackout SBR? That’s an easy answer. No.

So, here’s what I am doing. I’m going to make a legal AR-15 pistol, chambered in 300 Blackout using the 7.5-inch Aero upper assembly. That step requires no federal permission slips other than passing the standard NICS background check when I buy the lower receiver.

Once I have the lower receiver and know the serial number, I’m going to file a Form 1 application to build an official SBR using that receiver. I can get it engraved with my information in any of the 6,000+ hours that I’ll be waiting on my shiny new tax stamp. By starting with a fully functional pistol, I’ll avoid any risk of having only parts on hand that can be used to build an SBR. Better yet, I’ll have a fully functional pistol to use while I wait for my permission slip.

On the downside, I’ll ultimately need to buy two receiver extension buffer tubes. The pistol tubes are different, and for legal reasons, I wouldn’t want a rifle tube on there anyway until the tax stamp comes back. When I have my stamp, I’ll be able to install a rifle tube at which point I’ll have an extra pistol tube. They’re not that expensive, so it’s no big loss. Maybe I’ll use it for a future project.

Now I wait. And wait. And wait.