Davidson Defense Agamemnon 16-inch Pistol-Gas 1:8 .300 Blackout AR-15 Freefloat Picatinny & M-Lok Handguard Rifle Full Build Kit

Agamemnon 16-inch .300 Blackout AR-15 Full Build Kit

The Agamemnon is a Full Build Kit built around a 16-inch .300 Blackout barrel with an HBAR profile, paired with a 7075-T6 aluminum upper receiver finished in black anodizing. It pairs a 15-inch Unique-ARs Slim Molon Labe handguard with a GI birdcage flash hider at the muzzle, running on a pistol-length gas system. A complete bolt carrier group, Mil-Spec charging handle, complete Lower Parts Kit, carbine buffer-system components, and a SOPMOD-style collapsible 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

• 16-inch .300 Blackout barrel, 1:8 twist, Phosphate finish
• Pistol-length gas system with micro low-profile steel gas block
• 7075-T6 aluminum upper receiver, black anodized finish
• Unique-ARs Slim Molon Labe 15-inch handguard with Molon Labe cutout pattern
• GI birdcage flash hider, compatible with .300 Blackout, .308 Winchester, and 7.62x39
• SOPMOD-style collapsible stock with storage compartments and integrated QD mounts
• Complete Mil-Spec Lower Parts Kit and carbine buffer-system components included
• Lower receiver is not included.

Barrel and Gas System

The barrel runs 16 inches long, chambered in .300 Blackout and finished in phosphate with an HBAR profile. It carries a 1:8 twist rate suited to that chambering and a 5/8x24 muzzle thread. Gas cycles back to the action through a pistol-length system rather than the carbine or mid-length setup more common on a 16-inch barrel, running a pistol-length gas tube and a micro low-profile steel gas block sized to a .750-inch journal.

Upper Receiver and Handguard

The upper receiver is machined from 7075-T6 aluminum and finished in black anodizing, cut with M4 feed ramps for smooth feeding and fitted with a standard AR-15 forward assist assembly. The ejection port carries a standard .223/5.56 door with its rod and spring installed. Over the barrel sits a 15-inch Unique-ARs Slim Molon Labe handguard finished in black, featuring a slim profile with a Molon Labe cutout pattern along its length.

Muzzle Device

Capping the muzzle is a GI birdcage flash hider, compatible with .300 Blackout, .308 Winchester, and 7.62x39. It threads onto the barrel's 5/8x24 pattern and is secured in its final timed position with a 5/8-inch black crush washer.

Bolt Carrier Group and Charging Handle

A complete AR-15 bolt carrier group is included, made in the USA and listed for use across 5.56 NATO, .223 Remington, .300 Blackout, and .350 Legend. That broader listing describes the BCG itself; the barrel and chambering on this build remain .300 Blackout. A Mil-Spec AR-15 M4 charging handle rounds out the upper's operating components.

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. Behind it sits a Mil-Spec heavy-duty six-position adjustable buffer tube, holding a standard AR-15 carbine buffer weighing 3 ounces and a standard USA-made recoil spring. A standard castle nut and Mil-Spec AR-15/M16 receiver end plate secure the buffer tube assembly to the lower.

Stock

Capping off the rifle is a SOPMOD-style collapsible stock finished in black. It includes built-in storage compartments for small parts or batteries, along with integrated QD mounts for attaching a sling without extra hardware. It slides onto the six-position buffer tube included with this kit, giving the shooter adjustable length-of-pull for the final piece of the build.

Follow all manufacturer instructions and safe handling practices.

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

Lower receiver is not included.