Nefarious Arms HK416 / MR556 Barrel, 12.5" LIGHT, 5.56x45mm NATO

The Nefarious Arms HK416 / MR556 Barrel is engineered for shooters who demand uncompromising performance, precision, and durability. Proudly made in the USA, this barrel is crafted from premium 4150 Chrome Moly steel, cold-hammer-forged for strength, and chrome-lined to ensure years of reliable accuracy. Finished in sleek black Cerakote, it’s built to handle heavy use while maintaining peak performance. Whether you’re upgrading your HK416, MR556, or MR223, this barrel delivers the reliability and consistency you can trust.

ETA - SEPTEMBER 2025

Key Features:

• Caliber: 5.56x45mm NATO
• Barrel Length: 12.5"
• Profile: LIGHT
• Twist Rate: 1:7
• Gas Block Seat Diameter: 19mm (h6 Tolerance)
• Muzzle Threads: 1/2"x28
• Material: 4150 Chrome Moly 
• Finish: Black Manganese Phosphate
• Cold-Hammer-Forged for Strength and Consistency
• Chrome-Lined for Years of Accurate Shooting
• Made in USA

Compatible With:

• HK 416 A1, A3 
• HK MR556
• HK MR223