Davidson Defense Ruin w/SBA3 Brace 10.5-inch Carbine-Gas 1:8 5.56 NATO AR-15 Freefloat M-Lok Handguard Pistol Full Build Kit

Ruin SBA3 Brace 10.5-inch Carbine-Gas 1:8 5.56 NATO AR-15 Freefloat M-LOK Pistol Full Build Kit, Right-Side Charging

The Ruin is a 5.56 NATO AR-15 Full Build Kit built around a compact 10.5-inch carbine-length gas platform with a dedicated right-side charging billet upper receiver. The kit centers on a 10.5-inch cryogenically treated Sandel government profile steel barrel with a phosphate finish, 1:8 twist rate, and 1/2x28 thread pitch, paired with a salt bath nitride two-chamber muzzle brake and a black crush washer. A micro low-profile steel gas block at 0.750 diameter and a carbine-length stainless steel gas tube are included on the front end. The billet 6061 aluminum right-side charging upper receiver carries a Type III hardcoat anodized finish, accepts right-hand side charging bolt carrier groups only, and includes a timing plug, paired with a 10-inch freefloat M-LOK handguard in black. The Tactical Solutions Group side charging bolt carrier group compatible with 5.56 NATO and .223 Remington, with an included side charger BCG handle, completes the upper side. The lower hardware includes a complete Mil-Spec AR-15 lower parts kit with a fire control group and a Mil-Spec A2 style pistol grip in black, a heavy-duty 6-position carbine buffer tube, a standard 3 oz carbine buffer, a USA-made standard carbine recoil spring, an AR-15 M16 Mil-Spec end plate, and an AR-15 carbine castle nut. The SB Tactical SBA3 adjustable pistol stabilizing brace in black, compatible with Mil-Spec carbine buffer tubes, is included. Lower receiver not included.

Key Features

• 10.5-inch cryogenically treated Sandel government profile steel barrel, phosphate finish, 1:8 twist, 1/2x28 thread pitch, 5.56 NATO
• Carbine-length gas system
• Carbine-length stainless steel gas tube
• Micro low-profile steel gas block, 0.750
• Salt bath nitride two-chamber muzzle brake, 1/2x28, black crush washer included
• Billet 6061 aluminum right-side charging upper receiver, Type III hardcoat anodized, right-hand side charging BCG only, timing plug included
• 10-inch freefloat M-LOK handguard, black
• Tactical Solutions Group side charging bolt carrier group, 5.56 NATO and .223 Remington compatible, side charger BCG handle included
• Complete Mil-Spec AR-15 lower parts kit, fire control group included, Mil-Spec A2 style pistol grip, black
• Heavy-duty 6-position carbine buffer tube
• Standard carbine buffer, 3 oz
• Standard carbine recoil spring, made in USA
• AR-15 M16 Mil-Spec end plate
• AR-15 carbine castle nut
• SB Tactical SBA3 adjustable pistol stabilizing brace, black, Mil-Spec carbine buffer tube compatible

Perfect For

• Builders sourcing a complete 5.56 NATO AR-15 pistol full build kit with a dedicated right-side charging billet upper, cryogenically treated Sandel barrel, Tactical Solutions Group side charging BCG with handle, and SBA3 adjustable brace already included, pairing it with their own lower receiver
• Shooters building a compact 10.5-inch carbine-gas pistol platform who want the right-side charging bolt carrier group, salt bath nitride two-chamber muzzle brake, SBA3 adjustable brace, and complete lower parts kit covered in one kit with a Mil-Spec carbine buffer tube
• AR-15 pistol builders who want a right-side charging billet upper with a timing plug and cryogenically treated government profile barrel with a complete buffer system without sourcing components separately

Barrel and Muzzle Device

The 10.5-inch Sandel government profile barrel is chambered in 5.56 NATO and constructed from steel with a phosphate finish and cryogenic treatment. Cryogenic treatment subjects the barrel steel to deep cold temperatures to relieve residual stress in the metal structure. The twist rate is 1:8 and the thread pitch is 1/2x28, which matches the included salt bath nitride two-chamber muzzle brake. A black crush washer, a micro low-profile steel gas block at 0.750 diameter, and a carbine-length stainless steel gas tube cover the front end gas configuration on this carbine-length platform.

Right-Side Charging Billet Upper Receiver and Handguard

The billet 6061 aluminum upper receiver carries a Type III hardcoat anodized finish and is designed around a dedicated right-side charging system that accepts right-hand side charging bolt carrier groups only. A timing plug is included. The 10-inch freefloat M-LOK handguard is black with M-LOK attachment points along the body for accessory mounting. These two components define the exterior structure of the upper assembly on this AR-15 pistol platform.

Side Charging Bolt Carrier Group

The Tactical Solutions Group side charging bolt carrier group is compatible with 5.56 NATO and .223 Remington and includes a side charger BCG handle for use with right-side charging upper receiver platforms.

Lower Parts Kit and Buffer System

The complete Mil-Spec AR-15 lower parts kit covers the internal lower receiver components and includes a fire control group and a Mil-Spec A2 style pistol grip in black. The buffer system includes a heavy-duty 6-position carbine buffer tube, a standard 3 oz carbine buffer, a USA-made standard carbine recoil spring, an AR-15 M16 Mil-Spec end plate, and an AR-15 carbine castle nut. The SB Tactical SBA3 adjustable pistol stabilizing brace in black pairs with the included Mil-Spec carbine buffer tube and covers the rear brace interface for this 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. This upper receiver accepts right-hand side charging bolt carrier groups only.