Microbest BCG Mil-Spec OCKS C158 HPT/MPI 5.56 Bolt Carrier Group – Chrome w Phosphate Extractor
Estimated Ship Date 06/16/25
The Microbest BCG has been designed from the ground up with the most avid shooters in mind, using only the best materials available on the market today. The bolt assembly is machined from Carpenter No. 158® steel, shot-peened, MP marked, HP tested, and has a tool steel extractor that is machined from bar stock. Microbest is the OEM manufacturer and supplier of bolt carrier groups for a lot of popular rifle manufacturers, including but not limited to, Bravo Company Mfg and Sons of Liberty. Microbest is trusted to build a bolt carrier group that exceeds the MIL requirements from the right materials and processes with great attention to detail.
Upgrades Included Now:
- OCKS Gas Key Screws, Properly Staked by Microbest
- Sprinco 27001 5 Coil Extractor Spring
- Sprinco Extractor Insert
- Sprinco 27001 Ejector Spring
Bolt Assembly:
- Bolt precision machined from Carpenter 158 alloy and vibratory tumbled
- Heat-treated and shot-peened
- Individual high pressure/proof (HP) and individually magnetic particle inspection
- Ejector from S7 tool steel, heat-treated and shot-peened
- 5 Coil Sprinco Extractor Spring
- Sprinco Ejector Spring
- Gas Rings 3 Mil-Spec
- Hard chrome-plated finish w Phosphate Extractor
Carrier:
- Machined from AISI 8620 steel
- Full-auto M16 profile
- Heat treated and Carburized/strain relieved
- Precision ground gas key interface
- Gas key from 4140 steel Heat Treated
- OCKS Screws Staked, Phosphate Coated
- Hard chrome-plated finish
Misc:
- Cam pin from 4140 chromoly steel, heat-treated
- Firing pin from 8640 steel alloy, heat-treated, hard-chrome plated
- Firing pin retaining pin from 1038 carbon steel, heat-treated
ADDITIONAL INFORMATION
WEIGHT – 15 oz
BOLT MATERIAL – Carpenter 158 Steel
CARTRIDGE COMPATIBILITY – .223/5.56 NATO/.300 BLK
FINISH – Chrome w Phosphate Extractor
CARRIER PROFILE – M16
HIGH PRESSURE TESTED – Individually HP Tested
MAGNETIC PARTICLE INSPECTED – Magnetic Partical Inspected
PLATFORM – AR-15
BOLT FINISH – Chrome w Phosphate Extractor
Cameron Cowser (verified owner) –
Best bcg I own. Very gas efficient and cleans nicely. Staking is great. The phosphate exactor is a nice touch, and the springs and rings are sprinco. All for just $110 too. I need a few more.
SteveinUT (verified owner) –
The best BCG for the money on the market. Anytime someone asks me what BCG to buy, this is the one I recommend.
S Taylor (verified owner) –
I own 3, all from Midwest. Spectacular staking, machining and finish. All headspace fine. Midwest service is phenomenal.
John Bitwinski (verified owner) –
Every detail is as advertised. Tooling is without blemishes. Had I known about this BCG before I bought branded phosphated ones from DD and SOLGW, I’d have saved a bit of cash. That said, the DD and SOLGW BCGs are also top tier and are in use in my SBRs. If you are new to AR-15 builds and want a quality BCG at an affordable price, this is the one to buy.
bunny von apso (verified owner) –
Jeez, what a beauty. It’s a functional work of art. If you are on the fence, get one and find out.
BV-