How to Build an AR-15 Pistol
Woody's answers are based on published federal and state law. Not legal advice. Consult a licensed attorney for your specific situation.
Build an AR-15 pistol by assembling a lower receiver with pistol buffer tube, upper receiver with barrel under 16 inches, and pistol brace. Must follow ATF pistol regulations throughout the build process.
What This Means for Your Setup
AR-15 pistols offer compact firepower while remaining legally distinct from short-barreled rifles. The key difference lies in the stabilizing brace versus stock configuration and barrel length requirements. Understanding ATF classifications prevents inadvertent NFA violations during your build.
The Detail
Start with a stripped lower receiver that will be configured as a pistol from the beginning. You cannot convert a rifle lower to a pistol configuration legally, so ensure your lower receiver has never been assembled as a rifle. Install a pistol buffer tube system instead of a carbine or rifle buffer tube, as this prevents shouldering the weapon in a rifle-like manner.
Select an upper receiver with a barrel shorter than 16 inches. Popular choices include 10.5, 11.5, and 12.5 inch barrels, though you can go as short as you want. Shorter barrels will produce more muzzle flash and concussion, so consider a flash hider or muzzle brake designed for short barrels. The gas system length must match your barrel length, typically pistol-length gas systems for barrels under 10 inches and carbine-length for longer pistol barrels.
Attach a pistol stabilizing brace to your pistol buffer tube. These braces are designed to be strapped to your forearm for single-handed shooting stability. The brace cannot be designed to be shouldered like a traditional rifle stock, though incidental contact during firing is generally acceptable under current ATF guidance. Choose a brace that fits your intended use and comfort preferences.
Complete the build with standard AR-15 components including bolt carrier group, charging handle, and trigger group. Ensure your overall length exceeds 26 inches to avoid any-other-weapon classifications. If your pistol exceeds 26 inches overall length, you may legally add a vertical foregrip, but shorter pistols must use angled grips or hand stops to remain compliant.
Build Impact
Your component choices directly affect legal compliance and performance characteristics. Barrel length impacts ballistics and maneuverability, while brace selection affects usability and legal status. Always verify current ATF guidance before finalizing your configuration.