One Horse OH-CU04 AR-15 .300 AAC Blackout 16" 1:7 Complete Upper

The One Horse OH-CU04 is a complete AR-15 upper receiver chambered in .300 AAC Blackout and built around a 16-inch SOCOM-profile barrel machined from 4150 steel. The barrel wears a black nitride (melonite) finish for corrosion resistance and long service life, and the 1:7 rifling twist stabilizes a wide range of supersonic and subsonic .300 BLK bullet weights for both suppressed and unsuppressed use.

A pistol-length gas system keeps the action cycling reliably with subsonic loads, while the 15" M-LOK free-float handguard provides a slim, lightweight platform for mounting accessories along the sides and bottom. The handguard tops off with a full-length Picatinny rail, giving you an optic-ready setup right out of the box. The barrel is finished with 5/8x24 muzzle threads for direct-thread suppressor mounts or quick muzzle device swaps.

This drop-in upper ships fully assembled with a nitride BCG and charging handle, ready to mate with any mil-spec AR-15 lower receiver. Whether you are building a lightweight suppressor host, a hard-hitting .300 BLK hunting rig, or a short-barrel replacement, the One Horse OH-CU04 delivers a ready-to-shoot package at an everyday price.