Rosco Manufacturing Bloodline AR-15/M4 5.56 NATO 16" M4 Barrel - Nitride

The Rosco Manufacturing Bloodline is a precision 5.56 NATO drop-in barrel designed around the classic M4 carbine contour and a full 16" of usable barrel length. Sized for the AR-15 / M4 platform, it is built to deliver the velocity, balance, and accuracy that carbine-length shooters expect from a duty-grade barrel.

Rosco machines the Bloodline from 4150 CMV steel and treats the bore and exterior with a tough black nitride finish for long service life, reduced friction, and easier cleaning. The slim M4 profile keeps the front of the rifle light and well-balanced, while the 1:7 twist rate stabilizes the full range of 5.56 NATO bullet weights, from light varmint loads up through heavier open-base match projectiles.

This barrel is configured for a carbine-length gas system with a standard 1/2x28 muzzle thread, making it a direct replacement or upgrade for factory M4 carbine uppers. Properly sized gas ports are engineered to optimize cycling and reliability with a wide variety of ammunition and suppressor use.

Whether you are assembling a new carbine build, refreshing a worn-out factory barrel, or building a lightweight defensive rifle, the Rosco Manufacturing Bloodline 16" 5.56 NATO M4 barrel is a versatile, duty-ready choice.