NEW RELEASES

We’re continuously machining and developing new products in-house, expanding the lineup based on real performance needs. If you’re watching for updated configurations, new barrel profiles, or small-batch component runs, this is where they’ll show up.

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BARRELS

ALL PRODUCTS

Explore the full Nefarious lineup — premium components, accessories, and hard-use parts built for performance, precision, and reliability.

  • HK-platform parts and clone-correct components
  • Barrels, receivers, gas blocks and small parts
  • Tested fitment and verified compatibility
  • Trusted by builders, armorers, and serious shooters
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GAS BLOCKS

Reliable function for every build. Our Gas Blocks Collection is engineered for precision fit and dependable performance. Made from premium materials, these components ensure proper cycling and long-term durability whether you’re upgrading or starting a new rifle build. Trusted by shooters who demand reliability, Nefarious Arms gas blocks are built to perform.

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ARMORER'S TOOLS

Built for builders. Our Armorer’s Tools Collection includes the essential gear every gunsmith or enthusiast needs at the bench. From routine maintenance to full builds, these tools are designed for precision, durability, and reliability—helping you get the job done right.

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UPPER RECEIVER PARTS

Upper receiver components for both AR-15 and HK416 platforms — engineered for precision, compatibility, and proven durability.

  • Stripped and complete upper receivers
  • Gas pistons and piston rod assemblies
  • Barrel nuts and other upper accessories 
  • Gas blocks and alignment components
  • Parts selected for fitment, reliability, and platform-correct builds
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Let customers speak for us

from 41 reviews
Sal

Top notch work and awesome service!

Custom Barrel Dimpling
Custom Barrel Dimpling
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

MILITARY / LEO 15% DISCOUNT! Please contact us before placing your order for a discount code to apply at checkout.