Radical Defense MK1 Mod 1, Patrol, SBR, 5.56 NATO, 14.5″ Threaded Barrel, Black, 30 Rounds

The Radical Firearms PTRL 14.5″ SBR occupies the sweet spot of the AR-15 SBR market — the same barrel length as the M4 Carbine issued to U.S. military personnel, in an SBR configuration (stock + 14.5″ barrel without a permanently attached muzzle device). The M4’s 14.5″ barrel is the product of decades of combat experience: it provides reliable gas dwell time, excellent velocity retention for 5.56 NATO, and a length that balances maneuverability with practical effectiveness at 0–500 yards. The PTRL gives a civilian SBR owner that same proven formula at a price point that makes the $200 NFA stamp (now $0 under OBBBA) the biggest single expense rather than the rifle itself.

The 14.5″ SBR is arguably the best all-around AR-15 SBR configuration. It’s long enough for reliable function with the full range of 5.56 loads, suppressor-capable without the over-gassing issues of shorter barrels, and short enough to provide real handling advantages over a 16″ configuration in tight spaces.

Radical PTRL 14.5″ SBR Specifications

Ordering from Western Sport

Order online and we ship it to the licensed FFL dealer you choose near you — see how buying a gun online works. Western Sport has been a licensed FFL/SOT dealer since 2007, and everything we sell carries the full manufacturer warranty. Questions before you order? Send us a message.

FAQ — Radical PTRL 14.5″ SBR

Why NFA-register a 14.5″ barrel?

A 14.5″ barrel without a permanently attached muzzle device is a federally regulated SBR (under 16″ barrel length requires NFA registration). Rather than permanently attaching a muzzle device to bring the overall muzzle end to 16″, the PTRL is registered as an SBR — allowing the owner to run any muzzle device or suppressor without the permanent attachment. With the NFA stamp now $0 under OBBBA, there is no longer a financial argument against registering it properly as an SBR.

How does a 14.5″ SBR compare to a standard 16″ AR?

The 14.5″ barrel loses approximately 50–75 fps of muzzle velocity compared to a 16″ barrel — a modest tradeoff for 1.5 inches of additional length reduction. Gas dwell time and cycling reliability are essentially equivalent between 14.5″ and 16″. The 14.5″ SBR is meaningfully easier to handle inside vehicles and structures.

First NFA purchase? Here is how buying one works now.