Last reviewed: 2026-04-17 by Jake Terry, FFL07/SOT3, with hands-on install experience on AR/AK/Glock platforms.
The Aero Precision 5.56 BCG (APRH100615C) is a black-nitride-finished bolt carrier group engineered for AR-15 platforms chambered in .223 Remington, 5.56 NATO, and .300 Blackout. A bolt carrier group is the semi-automatic cycling assembly housed in the upper receiver; it rides the buffer system, strips rounds from the magazine, locks into battery, and extracts spent cases. This unit combines an 8620 tool steel carrier with a 9310 steel bolt, both coated in nitride—a low-friction finish that resists carbon fouling and extends service intervals between cleanings.
The Mechanism
Aero Precision machines the carrier from 8620 tool steel and cuts it to M16 profile, meaning full-auto-length tail for compatibility with select-fire lower receivers and enhanced bolt-velocity consistency in semi-automatic carbines. The gas key is properly staked with Grade 8 fasteners and sealed to prevent gas leakage. The bolt is machined from Carpenter 158 tool steel (the original spec text references 9310 steel in the spec table; we use the table value), shot-peened to relieve surface stress, and marked HP/MPI (high-pressure tested, magnetic-particle inspected) to confirm no sub-surface cracks. Forward assist serrations are cut into the carrier exterior. The extractor includes a black O-ring insert for tension retention. Weight is 11.52 oz.
Specs at a Glance
| Spec | Value |
|---|---|
| Platform | AR-15 |
| Cartridge Compatibility | .223/5.56 NATO/.300 BLK |
| Carrier Profile | M16 |
| Carrier Material | 8620 Tool Steel |
| Bolt Material | 9310 Steel |
| Finish | Nitride / Melonite |
| Bolt Finish | Nitride / Melonite |
| High Pressure Tested | HP Tested |
| Magnetic Particle Inspected | Magnetic Partical Inspected |
| Weight | 11.52 oz |
| MPN | APRH100615C |
| UPC | aprh100615c |
Install per Aero Precision’s torque specs: gas-key screws 35 in-lb, cam pin rotates freely, bolt locks into barrel extension with no play. Compatible with carbine-length and rifle-length gas systems. For builders replacing a factory BCG or assembling a new upper, this unit drops into any mil-spec AR-15 upper receiver. Browse our full selection of bolt carrier groups for additional calibers and finishes.
Safe Handling & Compliance
Bolt carrier groups are firearm components; installation requires field-stripping the upper receiver and verifying headspace with the installed barrel. Improper installation can cause failure to extract, failure to feed, or out-of-battery discharge. If you are unfamiliar with AR-15 disassembly, consult a qualified gunsmith or armorer.
- Observe the four universal firearm safety rules: treat every firearm as loaded, never point at anything you are not willing to destroy, keep your finger off the trigger until ready to fire, and know your target and what is beyond it.
- Verify current federal, state, and local laws regarding AR-15 ownership, configuration, and magazine capacity in your jurisdiction before ordering parts.
- Function-check the BCG after installation: pull the charging handle to the rear, release, and confirm the bolt locks into battery with the barrel extension. Cycle snap caps to verify feeding and extraction before live fire.
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