AIM AR/M16 H4 .223/5.56 Nitride 9310 MPI Bolt Carrier Group


$99.95    Quantity:    Add To Wish List

AIM H4 AR/M16 5.56/.223/.300 BLACKOUT caliber complete Black Nitrided Bolt Carrier Groups. A newly designed carrier reduces the surface area contact between the carrier and receiver walls. This improves performance and reliability as it reduces drag and creates "debris" channels to reduce malfunctions. Features; Shot peened, MPI (Magnetic Particle Inspected), 9310 Tool Steel Bolt; 8620 M16 carrier, Properly staked machined billet gas key hardened to USGI specifications fastened with Hardened Grade 8 Fasteners; Shot peened MPI (Magnetic Particle Inspected) Bolt. Extractor insert installed. Proudly made in the USA with a Lifetime Warranty.


3 to 9 $89.95
10 to 34 $89.95
35 or more $89.95

Black Nitride™ Process Specification and Information:

The Black Nitride™ process represents the most advanced refinement and enhancement of traditional Salt Bath Ferritic Nitrocarburization. AIM Bolt Carrier Group's Black Nitride™ process conforms to all aspects of Aerospace Materials Specification 2753C.
Black Nitride™ is a thermochemical diffusion process whereby nitrogen and carbon are diffused into the surface of the steel resulting in a harder more durable surface. This process is carried out at subcritical temperatures which eliminates any risk of distortion. Additionally, every part is quenched in an oxidizing salt bath proprietary to create a uniform Fe304 oxide layer that is both resistant to corrosion and visually appealing.
For many applications the Black Nitride™ process can replace traditional case hardening. The compound zone surface of Black Nitride™ will have a hardness of 55-70+RC. Depending on the substrate material the compound zone depth will be .0004”-.0008” with an effective case depth of .0004”-.003” and a total case depth that may exceed .010”

Specific Attributes Enhanced by Black Nitride™ processing includes:
  • Very high corrosion resistance – 96 hour minimum salt fog test per ASTM B117 most materials will exceed 200 hours minimum
  • Lowered coefficient of friction
  • Increased lubricity
  • Greater durability and abrasive resistance.
  • There will no distortion or dimensional change

The requirements for assembly of our Bolt Carrier Groups are much higher than most. Before assembling the gas key to the carrier, permatex NO.3D aviation is applied to form-a-gasket around the gas hole (per MIL-SPEC). Then Grade-8 hardware is used to attach the gas key, followed by properly staking per spec. When installing the extractor to the bolt, a crane-o-ring is inserted with the spring to insure proper ejection. Then high temperature grease is applied to the gas rings before inserting the bolt into the carrier, which allows for much smoother operation. These BCGs are inspected to the highest of standards, to insure a high quality product that is 100% reliable for our customer… PROUDLY MADE IN THE USA!

  • M16 style (Auto)
  • Machined from 8620 tool steel
  • Heat treated to military specifications
  • Machined from 9310 tool steel
  • Heat treated to military specifications
  • Shot Peened
  • Ground to meet military required tolerances
  • MPI (Mag Particle Inspected)
Gas Key
  • Machined from 4140
  • Heat treated to military specifications
  • Machined from 4140
  • Heat treated to military specifications
  • Shot peened
Firing Pin
  • Machined from 8640 tool steel
  • Heat treated to military specifications
  • Ground to meet military required tolerances
  • Coated with .0002”-.0003” of hard chrome per MIL-STD-171
Cam Pin
  • Machined from 4340
  • Quench and temper heat treat
  • Ground to meet military required tolerances


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