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Nefarious Arms HK416 / MR556 Barrel, 10.4" HEAVY, 5.56x45mm NATO

Nefarious Arms HK416 / MR556 Barrel, 10.4" HEAVY, 5.56x45mm NATO

$595.00 USD
$595.00 USD
Sale Sold out
Shipping calculated at checkout.

25 in stock

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 black manganese phosphate, it’s built to handle heavy use while maintaining peak performance. Whether you’re upgrading your HK416 or MR556, or this barrel delivers the reliability and consistency you can trust.

Key Features:

  • Caliber: 5.56x45mm NATO
  • Barrel Length: 10.4"
  • Profile: HEAVY
  • Twist Rate: 1:7
  • Barrel Extension: A1/A3 
  • 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
  • Weight: 26 oz.
  • Made in USA 🇺🇸

Compatible With:

  • HK416 A1/A3
  • HK MR556

Compatible Gas Blocks: 

  • HK A1/A3 
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Let customers speak for us

from 40 reviews
Meridian Ordnance LLC

Excellent option for the MR556A4 and 416 clones.

Nefarious Arms HK416 / MR556 Barrel, 14.5" LIGHT, 5.56x45mm NATO
Nefarious Arms HK416 / MR556 Barrel, 14.5" LIGHT, 5.56x45mm NATO
Sextus

Marvin and his products are top notch. Perfect fitment, excellent quality. These are the best barrels outside fo factory HK that one can buy!

Nefarious Arms HK416 A5 / G38 Barrel, 11", 5.56x45mm NATO
Nefarious Arms HK416 A5 / G38 Barrel, 11", 5.56x45mm NATO
Rick

Excellent parts / tools and fast shipping service

Nefarious Arms
Rick

For your barrel nut torquing a must have precision made tool. Excellent machined quality to use on a number of AR , KAC , Centurion Arms or HK variants.
Nicer than other popular and similar tools I have. protect your barrel extension index pin! Get one!

Reaction Rod – Armorer’s Multi-Platform Upper Receiver Holding Tool
Reaction Rod – Armorer’s Multi-Platform Upper Receiver Holding Tool
Brian Bell

Great part. Will install on my next build.

HK416 / MR556 / G36 Complete Gas Piston #50205381
HK416 / MR556 / G36 Complete Gas Piston #50205381
Brian Bell

Excellent service, fast shipping thank you!!

Nefarious Arms
Brian Bell

Excellent Quality, fast shipping what more could a man ask for. Thank you as always.

Barrel Nut - HK416 A5
Barrel Nut - HK416 A5
THANH D. LY

High quality and fast shipping

M110 / MKII Gas Block
M110 / MKII Gas Block
Anonymous

Quality is absolutely stellar. Nefarious arms nails it everytime

Barrel Nut - HK416 A5
Barrel Nut - HK416 A5
Anonymous

Quality is absolutely stellar. Nefarious arms nails it everytime

Enhanced Reliability Gas Piston
Enhanced Reliability Gas Piston
Zach Martin

Barrel is absolutely perfection. Knocked it out of the park

Nefarious Arms HK416 / MR556 Barrel, 10.4" HEAVY, 5.56x45mm NATO
Nefarious Arms HK416 / MR556 Barrel, 10.4" HEAVY, 5.56x45mm NATO
Zach Martin

Quality is absolutely stellar. Nefarious arms nails it everytime

Nefarious Arms
Anonymous

Quality is absolutely stellar. Nefarious arms nails it everytime

HK416 Ejection Port Axle
HK416 Ejection Port Axle
Anonymous

Quality is absolutely stellar. Nefarious arms nails it everytime

HK416, MR556 Piston Rod, Complete Assembly
HK416, MR556 Piston Rod, Complete Assembly
Dustin Villarreal

Helps immensely when pushing pins. Keeps everything stable and easy to work with. Keeps you from marring your barrels!

Gas Block Assembly Tool
Gas Block Assembly Tool