CMMG BARREL 16.1″ 350 LEGEND SBN

Description

This barrel sub-assembly is built around the .350 Legend cartridge, a straight-walled round that carries meaningful energy at hunting ranges while staying within velocity and case-geometry rules common to many Midwestern deer hunting states. That makes this a practical choice for anyone putting together a deer or hog rifle on an AR-15 platform where straight-walled cartridges are the practical or preferred option.

CMMG machines the barrel from 4140 chrome-moly steel, a material that balances toughness and machinability well for barrel stock. The Salt Bath Nitride finish — applied through a salt bath nitriding process rather than a chrome lining or coating — diffuses nitrogen into the steel surface itself, increasing surface hardness and corrosion resistance without meaningfully adding to the bore dimension or altering headspace. The result is a barrel that handles fouling and moisture without the bore-geometry concerns that can come with thick surface treatments.

The 1:16 twist rate is deliberately on the slower end for a rifle-caliber AR. The .350 Legend uses relatively heavy-for-caliber, large-diameter bullets at moderate velocities, and a slower twist rate stabilizes those projectiles without over-spinning lighter bullet weights. Ammunition selection at this twist rate favors factory .350 Legend hunting loads in the 145- to 180-grain range — the cartridge’s practical sweet spot — rather than lighter varmint-style projectiles.

The carbine-length gas port location keeps the operating cycle tuned for a 16-inch barrel without the added dwell-time complications of a pistol-length system on a barrel this long. The muzzle is threaded 1/2×28, the standard thread pattern for this bore diameter, so existing .350 Legend-compatible muzzle devices thread on without adapters. The barrel is designed to work with CMMG’s Mk4 upper receivers and ships without sights.