RailScales® est. 2014

Building An SBR

Building An SBR

March 13, 2019

As an AR owner, no doubt there’s some part of you that loves customizing your rifle. Even if it’s just swapping out the foregrip every now and then, the ease of use that the AR presents makes it simple to make the rifle truly yours.

Even for the most amateur of AR enthusiasts, the thought of building a short barrel rifle has likely crossed your mind at least once. It’s understandable. Compact rifles are commonly used by special forces and SWAT team. The allure of building one might be dampened by the reality of the work that goes into actually building one and filling out all the paperwork.

But surprisingly, it’s easier to put together an SBR than many realize and online form processing and submission makes this process faster than ever. Don’t believe us? Keep reading to see just how easy it is.

Note: This information is subject to change as a result of federal regulations and state and local laws. It is your responsibility to keep current on this information in order to build your SBR legally.

Planning, Not Purchases Come First

While it would be nice if you could simply walk into your nearest gun store and buy a short barrel rifle off the rack and leave the same day, it doesn’t quite work that way. Before you start dropping money on parts kits, receivers, barrels, and AR accessories, it’s important to start planning first.

Before you make a single purchase toward your new SBR, take a few minutes to fill out Form 1 from the Bureau of Alcohol, Tobacco, Firearms, and Explosives. This form may be 12 pages long but is pretty straightforward to fill out. Form 1 serves as your application to manufacture your new SBR or to register one with the ATF. Once completed, make three copies of this form. You’ll mail two to the ATF, and another to the Chief Law Enforcement Officer in your county, town, or city. It’s not a bad idea to have a fourth copy on hand for your own records.

In addition to Form 1, you’ll also need to mail in a $200 tax fee. This fee goes toward the tax stamp that shows that you are legally allowed to own the firearm.

Note: If you’ve already purchased the components to build an SBR before filling out, submitting, and getting approval on this paperwork, you are in violation of the Gun Control Act and you could be facing charges of unlawfully possessing a Class 3 Weapon.

File as an Individual Or as a Trust?

When filing to manufacture or register an SBR, you’ll have the choice of filing as a trust or as an individual. They both have their advantages and disadvantages.


When filing as an individual, you are filing to get the tax stamp in your name alone. That means that you’re the only one who can possess the weapon, and others can only use it while in your presence.


Trusts are legal entities and can own assets, like an SBR. Trusts ensure that the legal control of the asset can be transferred without the ownership of the weapon changing. You can also add and remove trustees, which allows others to use the SBR without you being present.

Your SBR Options

Once your application and tax fee has been submitted, you’ll have to wait a while for a response from the ATF, approximately three to six months. During this time, you can figure out how you’d like to build your SBR.

Commonly, you’ll find three methods for starting your SBR build. Each comes with its own benefits.

Build it From a Parts and Receiver Kit

Because the lower receiver of the AR is considered the registered part of the SBR, one of the easiest ways to build your SBR is on an unfinished, or 80 percent lower. By using an unmarked, incomplete lower, you can add your own serial number and trust name/individual name to it. The serial numbers and other information have to be at least .003" deep, and no smaller than 1/16th of an inch.

As soon as your tax stamp clears and your Form 1 is approved, you can take the lower to a gunsmith, or your workshop, and finish the receiver and add your markings to it. You’ll need to include the following information on your lower receiver:

  • Name of the gun maker (your name or the name of the trust)
  • The location of where the firearm was made
  • The caliber
  • Serial number
  • Model number

With this information engraved on the receiver, you can begin putting together your SBR. You can choose the parts that fit your needs and your vision and build a completely custom AR rifle.

Build it From a Pistol

AR pistols have become popular in recent years, especially with the development of stabilizers and braces that make it possible to shoot these pistols with one hand. The benefit of building from a pistol is that you have a legally functional firearm up to the point that your tax stamp arrives. Once that’s there, you can add a stock and make it an SBR.

Build it From a Rifle

With tax stamp in hand, you can take your 16" barrel carbine or rifle and simply add a shorter barrel.

Adding New Parts

Once you’ve got the basics of your short barrel rifle put together, it’s time to start adding parts and accessories. You’ll find that your rifle handles differently with a shorter barrel, so you may need to add parts like a foregrip or handstop that make it easier to manage the recoil. Additionally, you may need to tinker with your recoil spring, gas tube, and bolt carrier set up to get your rounds to cycle effectively and to limit the recoil. Really, you can mix and match until you find the right setup for your shooting preferences and style.

Outfit Your SBR With Parts From RailScales

Get a grip on your new SBR with the high-quality parts and rail accessories from RailScales. Our RSB is ideal for your short barrel rifle or PDW, and our Karve-P® handstop makes it easy to control the forend of your rifle. Order today.