Davidson Defense Vaultmaster 16-inch Carbine-Gas 1:16 .350 Legend AR-15 Freefloat Keymod Handguard Rifle Full Build Kit

Vaultmaster 16-inch Carbine-Gas 1:16 .350 Legend AR-15 Freefloat Keymod Rifle Full Build Kit

The Vaultmaster is a .350 Legend AR-15 Full Build Kit built around a 16-inch carbine-length gas platform. The kit centers on a 16-inch Balmung M4 profile steel barrel with a phosphate finish, 1:16 twist rate, and 5/8x24 thread pitch, paired with a black GI birdcage flash hider compatible with .350 Legend, .308 Winchester, 7.62x39, and .300 Blackout, and a black 5/8-inch 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 upper receiver is a USA-made billet aluminum slick side design with an anti-rotation cutout and no forward assist, paired with a 15-inch Trinity Force KMX freefloat Keymod handguard in black aluminum with a full-length Picatinny top rail. 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 buffer tube, a standard 3 oz carbine buffer, a USA-made standard AR-15 carbine recoil spring, an AR-15 M16 Mil-Spec receiver end plate, and an AR-15 carbine castle nut. The SOPMOD collapsible stock in black nylon reinforced polymer with integrated QD sling mounts in QPQ nitrided steel hardware and storage compartments rounds out the kit. Lower receiver not included.

Key Features

• 16-inch Balmung M4 profile steel barrel, phosphate finish, 1:16 twist, 5/8x24 thread pitch, .350 Legend
• Carbine-length gas system
• Carbine-length stainless steel gas tube
• Micro low-profile steel gas block, 0.750
• GI birdcage flash hider, black, 5/8x24, .350 Legend and .308 Winchester and 7.62x39 and .300 Blackout compatible, black crush washer included
• USA-made billet aluminum slick side upper receiver, anti-rotation cutout, no forward assist
• Trinity Force KMX 15-inch freefloat Keymod handguard, black aluminum, full-length Picatinny top rail
• USA-made complete AR-15 bolt carrier group, 5.56 NATO and .223 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 buffer tube
• Standard carbine buffer, 3 oz
• Standard AR-15 carbine recoil spring, made in USA
• AR-15 M16 Mil-Spec receiver end plate
• AR-15 carbine castle nut
• SOPMOD collapsible stock, black nylon reinforced polymer, integrated QD sling mounts with QPQ nitrided steel hardware, storage compartments

Perfect For

• Builders sourcing a complete .350 Legend AR-15 full build kit with a USA-made billet slick side upper, Trinity Force KMX Keymod handguard, and SOPMOD collapsible stock already included, pairing it with their own lower receiver
• Shooters building a 16-inch .350 Legend carbine-gas rifle platform who want a USA-made BCG, full-length Picatinny top rail Keymod handguard, and SOPMOD stock with integrated QD sling mounts covered in one kit
• AR-15 builders who want a .350 Legend Balmung M4 profile barrel with a compatible muzzle device and complete lower parts kit without sourcing components separately

Barrel and Muzzle Device

The 16-inch Balmung M4 profile barrel is chambered in .350 Legend and constructed from steel with a phosphate finish. The twist rate is 1:16 and the thread pitch is 5/8x24, which matches the included black GI birdcage flash hider. The flash hider is compatible with .350 Legend, .308 Winchester, 7.62x39, and .300 Blackout at the 5/8x24 thread pitch. A black 5/8-inch 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.

Slick Side Billet Upper Receiver and Handguard

The USA-made billet aluminum slick side upper receiver features an anti-rotation cutout and removes the forward assist housing from the upper receiver body for a clean exterior profile. The Trinity Force KMX 15-inch freefloat Keymod handguard is black aluminum with a full-length Picatinny top rail and Keymod attachment points along the body for accessory mounting. These two components define the exterior structure of the upper assembly on this .350 Legend 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.

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 USA-made standard AR-15 carbine recoil spring, an AR-15 M16 Mil-Spec receiver end plate, and an AR-15 carbine castle nut. The SOPMOD collapsible stock in black nylon reinforced polymer features integrated QD sling mounts with QPQ nitrided steel hardware and storage compartments, pairing with the included Mil-Spec carbine buffer tube and covering the rear stock interface for this build.

Follow safe handling and manufacturer instructions. Ensure compliance with all applicable federal, state, and local laws. Lower receiver not included.