Geissele Super HBAR MOD1 Complete Upper 5.56mm 14.5" Bbl (.812 Journal, 5/8x24) P&W Black Complete Upper Receiver 08-616B

The Geissele Super HBAR MOD1 Complete Upper 5.56mm 14.5" 08-616B is built around a heavy-profile barrel for the shooter who puts real volume through a rifle and needs the barrel to hold zero through it. The .812" gas journal isn't just a bigger number on a spec sheet, it's more mass around the gas port, which means better heat capacity and less barrel whip as round counts climb. This Geissele HBAR upper earns its name from that heavy barrel profile specifically.

That barrel is cold hammer forged and chrome lined with a 1:7 twist, stabilizing everything from lightweight 55gr to heavier 77gr loads without needing a barrel swap. A mid-length gas system paired with Geissele's Super Compact gas block keeps cycling smooth and the recoil impulse balanced, rather than the harsher snap you get from an under-tuned carbine-length setup on a heavy barrel. Weight comes in around 4.5-4.9 lbs for this Geissele 14.5 upper, enough heft to help manage heat without turning the rifle into a chore to carry.

The MK16 M-LOK free-float rail gives this Geissele Super HBAR Upper a rigid, modular mounting platform for optics and accessories, backed by a full-length picatinny top rail for anything that needs a bolt-on interface instead of M-LOK. It's compatible with standard AR-15 lowers, so there's no proprietary lower requirement holding the build together. Threaded 5/8x24 for muzzle devices, this Geissele Complete Upper covers the receiver, barrel, gas system, and rail, but ships without a bolt carrier group or charging handle, so plan to source those separately.

For custom rifle builds where barrel stability and sustained accuracy matter more than shaving ounces, this upper gives you the foundation to build around.

Key Features

• .812" gas journal heavy barrel for improved heat capacity
• Cold hammer forged and chrome lined, 1:7 twist
• Mid-length gas system with Super Compact gas block
• MK16 M-LOK free-float rail with full picatinny top rail
• Compatible with standard AR-15 lowers
• Threaded 5/8x24 for muzzle devices
• Weighs approximately 4.5-4.9 lbs
• Sold without bolt carrier group or charging handle