The Radical Defense MK1 MOD1 Patrol SBR is a semi-automatic 5.56 NATO rifle with a 14.5-inch barrel and a black finish (brand part no. MK1MOD1PATROL). A 14.5-inch barrel is the classic patrol carbine length, shorter than the usual 16 inches without giving up much velocity. Capacity is 30 rounds, the standard AR-15 magazine size. Radical Defense also offers a MK1 MOD1 Patrol Carbine with a 16-inch barrel; this short-barreled version is for the shooter who wants the trimmer length. It is a well-balanced 5.56 for patrol, home defense or general range work.

Key Specifications

• The chambering is 5.56 NATO, the standard AR-15 service cartridge with broad factory ammunition support.
• Barrel length is 14.5 inches, the patrol carbine length that makes this a short-barreled rifle.
• Capacity is 30 rounds, the standard AR-15 magazine size.
• The action is semi-automatic, one shot per trigger pull.
• The finish is black, the standard look for a duty-style AR-15.

Frequently Asked Questions

How is the Patrol SBR different from the MK1 MOD1 Patrol Carbine? The Patrol SBR has a 14.5-inch barrel, while the Patrol Carbine uses a 16-inch barrel. Both are 5.56 NATO with a 30-round capacity.

What barrel length does the Patrol SBR have? The barrel is 14.5 inches, chambered in 5.56 NATO.

Do I need ATF approval to buy this? No. As of October 9, 2026, ATF no longer requires Form 4 approval, registration or a tax stamp for short-barreled rifles. It transfers on a Form 4473 with a background check through a Class 3 (SOT) dealer. State and local laws still apply. Taking an SBR across state lines still requires an approved ATF Form 5320.20.

Buy the Radical Defense MK1 MOD1 Patrol SBR, 5.56 NATO, 14.5-Inch, Black

As of October 9, 2026, this short-barreled rifle transfers on a Form 4473 with a background check at your Class 3 (SOT) dealer, with no Form 4 or tax stamp; state and local laws still apply. It keeps the patrol rifle feel in a shorter package. Order through Radical Defense‘s short-barreled rifles lineup and our Lubbock, Texas team will handle the transfer, and it ships fast to your Class 3 dealer.