Davidson Defense Checkmate SBR Ready 8.5-inch Pistol-Gas 1:7 556 AR-15 Freefloat M-Lok Handguard Pistol Full Build Kit

Checkmate 8.5-inch Pistol-Gas 1:7 5.56 NATO AR-15 Freefloat M-LOK Pistol Full Build Kit, SBR Ready

The Checkmate is a 5.56 NATO AR-15 Full Build Kit configured for the SBR Ready designation, built around a compact 8.5-inch pistol-length gas platform. The kit centers on an 8.5-inch M4 contour barrel with a 1:7 twist rate and 1/2x28 thread pitch, paired with an A2 GI birdcage flash hider and a black 1/2-inch crush washer. A micro low-profile steel gas block at 0.750 diameter and a pistol-length gas tube are included on the front end. The 7075-T6 aluminum anodized upper receiver features M4 feed ramps, a forward assist, and an ejection port door assembly, paired with a 7-inch freefloat M-LOK handguard in black with a partial Picatinny top rail section. A USA-made complete AR-15 bolt carrier group compatible with 5.56 NATO, .223 Remington, .300 Blackout, and .350 Legend, 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, a standard 3 oz AR-15 carbine buffer, a USA-made standard AR-15 carbine recoil spring, a Mil-Spec AR-15 M16 receiver end plate, and an AR-15 carbine castle nut. This kit ships without a brace and is intended for customers selecting their own final setup. Lower receiver not included.

Key Features

• 8.5-inch M4 contour barrel, 1:7 twist, 1/2x28 thread pitch, 5.56 NATO
• Pistol-length gas system
• Pistol-length gas tube
• Micro low-profile steel gas block, 0.750
• A2 GI birdcage flash hider, 1/2x28, black 1/2-inch crush washer included
• 7075-T6 aluminum upper receiver, anodized, M4 feed ramps, forward assist, ejection port door assembly
• 7-inch freefloat M-LOK handguard, black, partial Picatinny top rail section
• USA-made complete AR-15 bolt carrier group, 5.56 NATO and .223 Remington and .300 Blackout and .350 Legend 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
• Standard AR-15 carbine buffer, 3 oz
• Standard AR-15 carbine recoil spring, made in USA
• Mil-Spec AR-15 M16 receiver end plate
• AR-15 carbine castle nut
• SBR Ready configuration

Perfect For

• Builders sourcing a complete 5.56 NATO AR-15 pistol full build kit with a 7075-T6 anodized upper receiver with forward assist, 8.5-inch M4 contour barrel, USA-made BCG compatible with multiple calibers, and 7-inch freefloat M-LOK handguard with partial Picatinny top rail section already included, pairing it with their own lower receiver and selecting their own rear brace or stock
• Shooters building a compact 8.5-inch pistol-gas 5.56 NATO platform who want the USA-made BCG, charging handle, and complete buffer system covered without a rear interface commitment and a freefloat M-LOK handguard with partial Picatinny top rail section
• AR-15 pistol builders who want a 5.56 NATO full build kit with a USA-made BCG compatible with multiple calibers in an SBR Ready configuration without sourcing components separately

Barrel and Muzzle Device

The 8.5-inch M4 contour barrel is chambered in 5.56 NATO with a 1:7 twist rate and 1/2x28 thread pitch, which matches the included A2 GI birdcage flash hider. A black 1/2-inch crush washer, a micro low-profile steel gas block at 0.750 diameter, and a pistol-length gas tube cover the front end gas configuration on this pistol-length platform.

Upper Receiver and Handguard

The 7075-T6 aluminum upper receiver carries an anodized finish with M4 feed ramps, a forward assist, and an ejection port door assembly. The 7-inch freefloat M-LOK handguard is black with a partial Picatinny top rail section 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-15 pistol platform.

Bolt Carrier Group and Charging Handle

The USA-made complete AR-15 bolt carrier group is compatible with 5.56 NATO, .223 Remington, .300 Blackout, and .350 Legend. A Mil-Spec AR-15 M4 charging handle is included to complete the upper component set.

SBR Ready Configuration

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, a standard 3 oz AR-15 carbine buffer, a USA-made standard AR-15 carbine recoil spring, a Mil-Spec AR-15 M16 receiver end plate, and an AR-15 carbine castle nut. This kit ships without a brace, with the brace or stock selection remaining with the buyer.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. Ships without a brace. Do not attach a stock unless compliant with applicable laws. Lower receiver not included.