Geissele Super Duty 5.56 AR-15 Rifle Build Kit (05-1626B)

The Geissele Super Duty Build Kit is a complete 5.56mm upper and the parts to finish an AR-15 lower.

The upper has a Nanoweapon-coated HUXWRX Flash Hider QD muzzle device on a manganese phosphate coated, cold hammer forged, chrome lined Geissele barrel with a 1-7 twist, made in North Wales, PA. It uses a Geissele Length gas system and the Geissele Super Compact Gas Block.

The included MK16 Super Modular rail mates with the upper receiver via a center aligning tab, which prevents rail rotation. It is a variant of the SMR MK16 fielded by USASOC.

The upper uses the Geissele REBCG (Reliability Enhanced Bolt Carrier Group). The Nanoweapon-coated BCG has a properly torqued and staked, chrome lined gas key and a Nanoweapon-coated tool-steel cam pin. Extended upper rails add stability and improve feeding. The Geissele Stressproof Bolt is made from Carpenter 158+ steel, developed with Carpenter Steel metallurgists for fewer impurities and greater fatigue resistance. Each bolt is inspected, high-pressure tested, mag particle inspected and Nanoweapon coated.

The Geissele Ultra Duty Lower Parts Kit includes all the internal parts needed to complete or rebuild a lower receiver, machined in North Wales, PA. Key components are stainless steel for corrosion resistance and service life. It includes the Maritime Bolt Catch, with aggressive texturing and extended paddles, and the Ambidextrous Super Configurable Safety, whose levers can be swapped and which gives positive tactile feedback at safe and fire. The takedown pins and mag release button have the same "tank tread" texture as the Maritime Bolt Catch. The kit also includes Geissele's Ultra Precision Trigger Guard, 5-axis machined from billet 7075-T6 aluminum with Type 3 hardcoat anodize.

The trigger is the SSA-E X with Lightning Bow®, normally exclusive to Super Duty firearms: a nanocoated two-stage trigger with a wide, bow-shaped body between a classic M4 trigger and a flat trigger, with a light first-stage take-up and a crisp second-stage break.

The Geissele Premium Mil-Spec Buffer Tube is machined from 7075-T6 aluminum with Type 3 hardcoat anodize. It is carbine length, mil-spec diameter, with six stock positions, and comes with a mil-spec castle nut and end plate.

The Geissele Super 42 Buffer Spring and Buffer Combo uses a spring of three independent wire strands, like the German MG42 machine gun's. The strands flex separately, damping harmonics and absorbing energy, which reduces the chance of spring failure. Compared with a stock spring it loses less length and force over a given round count and removes the spring "twang" felt through the buttstock. Its average return force is 15% higher than a standard buffer spring, which helps strip rounds from the magazine with a dirty rifle or steel-case ammo.

The B5 stock, used by the U.S. military, is a reinforced polymer stock for AR-15/M4 receiver extensions with an improved cheek weld. Two waterproof compartments hold 2 AA or 3 CR-123 batteries. It has snag-resistant contours, a Sure-Grip stock latch for length-of-pull adjustment, an anti-slip rubber recoil pad, a stainless-steel QD swivel mount and two molded 1¼" sling slots.

The Geissele A17 Grip has a 1911-style grip angle for the AR15/M4, with anti-slip texturing and a thicker palm swell for a high grip.