CMMG 300 Blackout 8" Pistol Barrel Sub-Assembly

CMMG 300 Blackout Barrel Sub-Assembly

This is a complete barrel sub-assembly designed for AR-15 upper receivers. It features an 8-inch barrel in 300 Blackout—an excellent choice for short-range hunting, home defense, and suppressed shooting.

Key Features

• Caliber: 300 Blackout
• Barrel Length: 8 inches
• Material: 4140 chromoly steel with black nitride finish
• Profile: Medium taper
• Extension: M4 barrel extension, factory installed
• Headspace: Factory headspaced and ready to use

What You Get

This sub-assembly arrives as a complete unit with the barrel extension already installed and properly headspaced. Simply integrate it into your AR-15 upper receiver—no additional fitting or headspacing work required.

Why 300 Blackout?

The 300 Blackout cartridge excels in short-barreled rifles. It delivers excellent performance with subsonic ammunition when paired with a suppressor, making it ideal for tactical applications and hunting. The 8-inch barrel length keeps your rifle compact while maintaining reliable function.

Build Quality

CMMG barrels are manufactured to exacting standards. The black nitride finish provides corrosion resistance and durability, while the 4140 chromoly steel ensures longevity under demanding use.