Davidson Defense Col Cooper w/SBA5 Brace 10.5-inch Carbine-Gas 1:24 .450 Bushmaster AR-15 Freefloat M-Lok Handguard Pistol Full Build Kit

Davidson Defense Col Cooper SBA5 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 steel with a 1:24 twist rate and 5/8x32 thread pitch, paired with a KAK .458 compensator and a black crush washer. A low-profile gas block at 0.750 diameter and a stainless steel gas tube are included on the front end. The Panhead billet upper receiver features an enlarged .458 ejection port door, paired with a 10-inch ultra-lightweight minimalist freefloat M-LOK handguard with a partial top rail and no anti-rotation tabs. A .458 SOCOM and .450 Bushmaster compatible bolt carrier group and a Mil-Spec AR-15 M4 charging handle complete the upper side. The lower hardware includes a complete Mil-Spec AR-15 lower parts kit, a Mil-Spec heavy-duty 6-position buffer tube, a standard 3 oz carbine buffer, a standard AR-15 carbine recoil spring, a Mil-Spec M16 style receiver end plate, and a Mil-Spec AR-15 castle nut. The SB Tactical SBA5 pistol stabilizing brace in black is included. Lower receiver not included.

Key Features

• 10.5-inch H-Bar barrel, steel, 1:24 twist, 5/8x32 thread pitch
• Carbine-length gas system
• Stainless steel gas tube
• Low-profile gas block, 0.750
• KAK .458 compensator, 5/8x32, black crush washer included
• Panhead billet upper receiver, enlarged .458 ejection port door
• 10-inch ultra-lightweight minimalist freefloat M-LOK handguard, partial top rail, no anti-rotation tabs
• .458 SOCOM and .450 Bushmaster compatible bolt carrier group
• Mil-Spec AR-15 M4 charging handle
• Complete Mil-Spec AR-15 lower parts kit
• Mil-Spec heavy-duty 6-position buffer tube
• Standard carbine buffer, 3 oz
• Standard AR-15 carbine recoil spring
• Mil-Spec M16 style receiver end plate
• Mil-Spec AR-15 castle nut
• SB Tactical SBA5 pistol stabilizing brace, black

Perfect For

• Builders sourcing a complete .450 Bushmaster AR-15 pistol kit with an SBA5 brace and lower parts kit already included, pairing it with their own lower receiver
• Shooters building a compact 10.5-inch .450 Bushmaster platform who want the Panhead billet upper, enlarged ejection port, and KAK compensator covered in one kit
• AR-15 builders who want an SB Tactical SBA5 brace and .450 Bushmaster bolt carrier group included without sourcing components separately

Barrel and Muzzle Device

The 10.5-inch H-Bar barrel is chambered in .450 Bushmaster and constructed from steel with a 1:24 twist rate. The thread pitch is 5/8x32, which matches the included KAK .458 compensator. A black crush washer, a low-profile gas block at 0.750 diameter, and a stainless steel gas tube cover the front end gas configuration on this carbine-length platform.

Panhead Upper Receiver and Handguard

The Panhead billet upper receiver features an enlarged .458 ejection port door to accommodate the .450 Bushmaster cartridge. The 10-inch ultra-lightweight minimalist freefloat M-LOK handguard features a partial top rail and no anti-rotation tabs, providing M-LOK attachment points along the 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 bolt carrier group is compatible with .458 SOCOM and .450 Bushmaster, covering the upper internal components beyond the barrel and handguard. A Mil-Spec AR-15 M4 charging handle is included to complete the upper component set.

Lower Parts Kit and Buffer System

The complete Mil-Spec AR-15 lower parts kit covers the internal lower receiver components. The buffer system includes a Mil-Spec heavy-duty 6-position buffer tube, a standard 3 oz carbine buffer, a standard AR-15 carbine recoil spring, a Mil-Spec M16 style receiver end plate, and a Mil-Spec AR-15 castle nut. The SB Tactical SBA5 pistol stabilizing brace in black 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. Verify local and state laws regarding pistol brace use and classification.