Davidson Defense Lock Jaw 18-inch Rifle-Gas 1:7 22 ARC AR-15 KeyMod Handguard Rifle Full Build Kit

Lock Jaw 18-inch .22 ARC AR-15 Full Build Kit

The Lock Jaw is a Full Build Kit built around an 18-inch heavy .22 ARC barrel, machined from 416R stainless steel, paired with a Black Diamond Series slick-side billet upper receiver, made in the USA. It pairs a Trinity Force ECHO 15-inch KeyMod rail with a 3-port compensator at the muzzle, running on a rifle-length gas system. A 6.5 Grendel II bolt carrier group, Mil-Spec charging handle, complete Lower Parts Kit, carbine buffer-system components, and an Adaptive Tactical EX Performance adjustable stock round out the rest of the rifle. The lower receiver is not included, leaving the buyer to select and supply that component separately.

Key Features

• 18-inch heavy .22 ARC barrel, 1:7 twist, 416R stainless steel
• Rifle-length gas system with micro low-profile steel gas block
• Black Diamond Series slick-side billet upper receiver, made in the USA
• Trinity Force ECHO 15-inch KeyMod rail
• 3-port compensator, stainless steel
• 6.5 Grendel II bolt carrier group, QPQ nitride finish
• Adaptive Tactical EX Performance adjustable stock, model AT-02012-B
• Complete Mil-Spec Lower Parts Kit and carbine buffer-system components included
• Lower receiver is not included.

Barrel and Gas System

The barrel runs 18 inches long, chambered in .22 ARC and machined from 416R stainless steel with a heavy profile, giving it the mass to handle sustained strings of fire while promoting accuracy at this platform's extended effective range. It carries a 1:7 twist rate, matched to stabilize the .22 ARC's bullet options, and a 1/2x28 muzzle thread. Gas cycles back to the action through a rifle-length system, running a stainless steel rifle-length gas tube and a micro low-profile steel gas block sized to a .750-inch journal, keeping the profile low under the handguard.

Upper Receiver and Handguard

The upper receiver is a Black Diamond Series slick-side billet unit, made in the USA and machined without a forward assist, giving the receiver's side profile a clean, uninterrupted look. The ejection port carries a standard .223/5.56 door with its rod and spring installed, handling case ejection and keeping debris out of the action when closed. Over the barrel sits a Trinity Force ECHO 15-inch rail, using a KeyMod attachment system along its length for mounting rail sections, lights, and other accessories exactly where the shooter wants them.

Muzzle Device

Capping the muzzle is a 3-port compensator machined from stainless steel, built to help manage muzzle rise across strings of fire. It threads onto the barrel's 1/2x28 pattern and is secured with the included stainless steel 1/2-inch crush washer, locking its ports in the correct orientation.

Bolt Carrier Group and Charging Handle

An AR-15 6.5 Grendel II bolt carrier group is included, finished in QPQ nitride and listed for use across 6.5 Grendel II and .22 ARC platforms. That broader listing describes the BCG itself; the barrel and chambering on this build remain .22 ARC. A Mil-Spec AR-15 M4 charging handle rounds out the upper's operating components, giving the shooter a standard, reliable way to charge the action.

Lower Parts Kit and Buffer System

A complete Mil-Spec AR-15 Lower Parts Kit covers the fire-control and lower-control internals needed once a lower receiver is on hand, giving the buyer everything required to bring a stripped lower to life aside from the receiver itself. Behind it sits a Mil-Spec heavy-duty six-position buffer tube, holding a standard AR-15 carbine buffer weighing 3 ounces and a standard USA-made recoil spring, which together manage the reciprocating mass of the action during cycling. An AR-15 carbine castle nut and Mil-Spec AR-15/M16 receiver end plate secure the buffer tube assembly to the lower, locking the whole rear assembly firmly in place.

Stock

Capping off the rifle is an Adaptive Tactical EX Performance adjustable stock, model AT-02012-B, finished in black. It's built for a Mil-Spec buffer tube, matching the buffer tube included with this kit, and adjusts to let the shooter dial in the length-of-pull that fits them best.

Follow all manufacturer instructions and safe handling practices.

Ensure compliance with all applicable federal, state, and local laws.

Lower receiver is not included.