Davidson Defense Col Cooper w/SBA3 Brace 10.5-inch Carbine-Gas 1:24 .450 Bushmaster AR-15 Freefloat M-Lok Handguard Pistol Full Build Kit

Davidson Defense Col Cooper SBA3 Brace 10.5-inch .450 Bushmaster AR-15 Freefloat M-Lok Pistol Full Build Kit

The Davidson Defense Col Cooper is a .450 Bushmaster AR-15 Full Build Kit built around a compact 10.5-inch carbine-length gas platform. The kit centers on a 10.5-inch H-Bar barrel in 4150 Chrome Moly Vanadium with a phosphate finish, 1:24 twist rate, and 5/8x32 thread pitch, paired with a KAK .458 compensator also threaded at 5/8x32. A low-profile gas block at 0.750 diameter is included on the front end. The upper receiver is 6061-T6 aluminum with a Type III hardcoat anodized finish, paired with a freefloat M-Lok handguard. A .458 SOCOM and .450 Bushmaster bolt carrier group in 9310 alloy steel with a nitride finish and a Mil-Spec AR-15 charging handle complete the upper side. The lower hardware includes a Mil-Spec heavy-duty 6-position buffer tube, a standard 3 oz carbine buffer, a recoil spring, an AR-15 M16 Mil-Spec receiver end plate, and a castle nut. The SB Tactical SBA3 adjustable pistol stabilizing brace is included. Lower receiver not included.

Key Features

• 10.5-inch H-Bar barrel, 4150 Chrome Moly Vanadium, phosphate finish, 1:24 twist, 5/8x32 thread pitch
• Carbine-length gas system
• Low-profile gas block, 0.750
• KAK .458 compensator, 5/8x32
• 6061-T6 aluminum upper receiver, Type III hardcoat anodized
• Freefloat M-Lok handguard
• .458 SOCOM and .450 Bushmaster bolt carrier group, 9310 alloy steel, nitride finish
• Mil-Spec AR-15 charging handle
• Mil-Spec heavy-duty 6-position buffer tube
• Standard carbine buffer, 3 oz
• AR-15 M16 Mil-Spec receiver end plate
• Castle nut
• SB Tactical SBA3 adjustable pistol stabilizing brace

Perfect For

• Builders sourcing a complete .450 Bushmaster AR-15 pistol kit and pairing it with their own lower receiver
• Shooters building a compact 10.5-inch .450 Bushmaster platform with an SB Tactical SBA3 brace already included
• AR-15 builders who want a .450 Bushmaster bolt carrier group and KAK compensator covered in one kit

Barrel and Front End Components

The 10.5-inch H-Bar barrel is chambered in .450 Bushmaster and constructed from 4150 Chrome Moly Vanadium with a phosphate finish. The twist rate is 1:24 and the thread pitch is 5/8x32, which matches the included KAK .458 compensator. A low-profile gas block at 0.750 diameter is included and pairs with the carbine-length gas system on this barrel.

Upper Receiver and Handguard

The upper receiver is 6061-T6 aluminum with a Type III hardcoat anodized finish. The freefloat M-Lok handguard provides M-Lok attachment points along the rail body for accessory mounting. These two components define the exterior structure of the upper assembly on this .450 Bushmaster platform.

Bolt Carrier Group and Charging Handle

The .458 SOCOM and .450 Bushmaster bolt carrier group is 9310 alloy steel with a nitride finish, spec-matched to the .450 Bushmaster platform. A Mil-Spec AR-15 charging handle is included to complete the upper component set. These two parts cover the upper internal components beyond the barrel and handguard.

Buffer System and Brace

The buffer system in this kit includes a Mil-Spec heavy-duty 6-position buffer tube, a standard 3 oz carbine buffer, a recoil spring, an AR-15 M16 Mil-Spec receiver end plate, and a castle nut. The SB Tactical SBA3 adjustable pistol stabilizing brace rounds out the kit, providing an adjustable rear interface for the pistol platform.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. Lower receiver not included.