Description

The Hydra Quick-Change Upper Receiver Assembly (16″) is designed around the same QCB-D foundation as the rest of the Hydra system, scaled for a rifle-length barrel. The intent is simple: give users one upper that can run multiple calibers while keeping each cartridge operating the way it should.

For rifle calibers, the upper uses a direct-impingement system, maintaining familiar function and recoil characteristics. For pistol calibers, the platform switches to direct blowback, keeping those configurations straightforward and reliable. Each caliber stays true to proven operating methods rather than forcing a compromise system.

In its 16-inch rifle configuration, this upper is well suited for shooters who want a traditional rifle feel with the added benefit of quick caliber changes. The longer barrel length provides consistent handling across the rifle calibers while still allowing pistol calibers to be run on the same upper when configured accordingly.

The quick-change design is built in from the start. Caliber swaps are part of normal use, not an armorer-only task, allowing the upper to adapt as needs change over time.

Available Calibers

Rifle calibers (Direct Impingement):

• 5.56 NATO

• 300 Blackout

• 7.62×39

Pistol calibers (Direct Blowback):

• 9mm

• 10mm

• .45 ACP

What’s Included (16″ Configuration)

• Hydra Quick-Change Upper Receiver (QCB-D)

• 16-inch barrel matched to selected caliber

• Standard flash hider

• Appropriate bolt carrier group for selected caliber

• Charging handle

Notes on Use

This upper is intended to be used as part of the Hydra modular ecosystem. The same quick-change principles apply across calibers, allowing end users to reconfigure the platform without permanent modifications or specialized tools.

7.62 x 39 models required to use exclusively the Hydra 15 lower with AK pattern magazine well.