Davidson Defense Doomspire w/SBA5 Brace 6-inch 1:10 9MM AR-9 Freefloat Tubular M-Lok Handguard Pistol Full Build Kit

Doomspire SBA5 Brace 6-inch 1:10 9mm AR-9 Freefloat Tubular M-LOK Pistol Full Build Kit

The Doomspire is a 9mm AR-9 Full Build Kit built around a compact 6-inch direct blowback platform. The kit centers on a 6-inch 4150 CrMoV steel barrel with a nitride finish, 1:10 twist rate, and 1/2x28 thread pitch, paired with a muzzle-mounted fake can. The 7075-T6 aluminum hardcoat anodized upper receiver features M4 feed ramps, a forward assist, and an ejection port door assembly, paired with a 10-inch aluminum tubular freefloat M-LOK handguard with a 1.77-inch internal diameter and suppressor-ready clearance. A complete 9mm nitride bolt carrier group in 8620 alloy steel with an external extractor compatible with Glock and Colt pattern magazines, 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 aluminum carbine buffer tube, an AR-15 9mm carbine buffer, a standard AR-15 carbine recoil spring, a Mil-Spec AR-15 M16 receiver end plate, and a Mil-Spec AR-15 carbine castle nut. The SB Tactical SBA5 adjustable pistol stabilizing brace in black is included. Lower receiver not included.

Key Features

• 6-inch 4150 CrMoV steel barrel, nitride finish, 1:10 twist, 1/2x28 thread pitch, 9mm
• Direct blowback platform
• Muzzle-mounted fake can, 1/2x28
• 7075-T6 aluminum upper receiver, hardcoat anodized, M4 feed ramps, forward assist, ejection port door assembly
• 10-inch aluminum tubular freefloat M-LOK handguard, 1.77-inch internal diameter, suppressor-ready clearance
• Complete 9mm nitride bolt carrier group, 8620 alloy steel, external extractor, Glock and Colt pattern magazine compatible
• Mil-Spec AR-15 M4 charging handle
• Complete Mil-Spec AR-15 lower parts kit
• Mil-Spec heavy-duty 6-position aluminum carbine buffer tube
• AR-15 9mm carbine buffer
• Standard AR-15 carbine recoil spring
• Mil-Spec AR-15 M16 receiver end plate
• Mil-Spec AR-15 carbine castle nut
• SB Tactical SBA5 adjustable pistol stabilizing brace, black

Perfect For

• AR-9 pistol builders sourcing a complete 9mm blowback full build kit with a 7075-T6 hardcoat anodized upper receiver with forward assist, 6-inch nitride 4150 CrMoV barrel, 10-inch tubular freefloat M-LOK handguard with suppressor-ready clearance, nitride BCG compatible with Glock and Colt pattern magazines, and SBA5 adjustable brace on a Mil-Spec carbine buffer tube already included, pairing it with their own lower receiver
• Shooters building a compact 6-inch 9mm direct blowback AR-9 pistol platform who want the AR-9 BCG, charging handle, complete lower parts kit, and SBA5 adjustable brace covered in one kit with a suppressor-ready tubular freefloat M-LOK handguard
• AR-9 PCC pistol builders who want a complete blowback full build kit with a Glock and Colt pattern magazine compatible BCG and a suppressor-ready 10-inch tubular freefloat M-LOK handguard with an SBA5 adjustable brace without sourcing components separately

Barrel and Muzzle Device

The 6-inch barrel is chambered in 9mm and constructed from 4150 CrMoV steel with a nitride finish. The twist rate is 1:10 and the thread pitch is 1/2x28, which matches the included muzzle-mounted fake can. The direct blowback platform design addresses the 9mm cartridge in an AR-9 pistol caliber build without a gas system.

Upper Receiver and Handguard

The 7075-T6 aluminum upper receiver carries a hardcoat anodized finish with M4 feed ramps, a forward assist, and an ejection port door assembly. The 10-inch aluminum tubular freefloat M-LOK handguard features a 1.77-inch internal diameter with suppressor-ready clearance and M-LOK attachment points along the body for accessory mounting. These two components define the exterior structure of the upper assembly on this AR-9 pistol platform.

Bolt Carrier Group and Charging Handle

The complete 9mm nitride bolt carrier group is 8620 alloy steel with a nitride finish and features an external extractor compatible with both Glock and Colt pattern magazines. 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 aluminum carbine buffer tube, an AR-15 9mm carbine buffer, a standard AR-15 carbine recoil spring, a Mil-Spec AR-15 M16 receiver end plate, and a Mil-Spec AR-15 carbine castle nut. The SB Tactical SBA5 adjustable pistol stabilizing brace in black pairs with the included Mil-Spec carbine buffer tube and covers the rear brace interface for this AR-9 pistol lower build kit.

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. Verify compatibility with your specific 9mm AR-9 lower receiver and magazine pattern before use.