The AR-15 shares many similarities across its available configurations. Many parts are interchangeable across builds, while some parts are specific to the configuration. For example, which gas system can be installed on what barrels? Which buffer is required for the gas system and caliber of choice?
Let's explain the differences between rifle and pistol build kits!
The AR-15 Rifle Build Kit explained
The AR-15 can technically be categorized into three configurations: Rifle, short-barreled rifle (SBR), and pistol. Those last two share many similarities (and a set of legal challenges) so let's break down the most popular, first.
AR-15 Rifle Build Kit minimum barrel length
Our AR-15 Rifle Build Kits include, at minimum, a full-built upper receiver that features a barrel length of at least 16 inches. This is the minimum barrel length required for an AR-15 to be legally considered a rifle. The overall length of the rifle must also be at least 26 inches.
Getting around minimum barrel length
AR-15 Rifle Build Kits can be manufactured with a 14.5" barrel and a pinned muzzle device measuring at least 1.5", bringing total barrel length to 16". Theoretically, your AR-15 rifle's barrel can be any length, but you'll need a permanently affixed muzzle device to bring total length to 16". Using any barrel that's shorter will constitute the creation of an AR-15 SBR, and that requires ATF paperwork and the payment of a $200 tax stamp.
The AR15 Pistol Build Kit explained
The AR15 Pistol Build Kit can be ordered with any barrel length! These build kits are perfect for three-gun competitions, home defense, and much more. But building your next piece with an AR15 Pistol Build Kit means avoiding certain features and parts that could land you in legal hot water.
For example, any AR-15 Pistol Build Kit will not include a buttstock of any kind. Building an AR-15 with a barrel length shorter than 16" and affixing a buttstock constitutes the manufacturing of - you guessed it - an SBR.
You can, however, get away with using a pistol brace. Pistol braces are legally allowed to be shouldered like a buttstock (the ATF has clarified this), and the finished firearm will appear and function similarly to an SBR, minus all that paperwork and legalese.
So, you want to build an AR-15 SBR
Let's say you want to pick up an AR-15 Pistol Build Kit and slap a proper buttstock on it. You certainly can, though you'll need to follow some important steps to tow the line of the law:
- You'll need to download, fill out, and submit ATF Form 5320.1 ((Form 1") to the Bureau of Alcohol, Tobacco, and Firearms. This is the Application to Make and Register a Firearm. You'll also need to provide a 2x2 passport-quality photo, provide fingerprints, and you'll need a signature from your local chief law enforcement officer.
- You'll need to mail in your Form 1 paperwork with a $200 tax fee to be paid to the ATF. The fee goes toward a "tax stamp" showing you legally own your SBR.
- You'll need to download, fill out, and provide to the ATF a Certification of Compliance with 18 U.S.C 922 (g)(5)(B). This form simply states you're a legal United States Citizen.
- Receive your tax stamp and build (and engrave) your SBR! You'll need to engrave your SBR with your name and other serialization requirements. You can technically start to build your SBR as a rifle or pistol - you simply can't install any of the "SBR" parts until you receive your tax stamp.