Microbest Full-Auto M16 Bolt Carrier Group, Chrome & Phosphate Extractor
The Microbest Bolt Carrier Group is the measuring stick by which all others are compared.
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.
Assembled with Sprinco springs and inserts for longevity and reliability.
Specifications:
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
- Extractor from 4340, heat-treated and shot-peened, manganese phosphate finish
- Ejector from S7 tool steel, heat-treated and shot-peened
- Hard chrome-plated finish
Carrier:
- Machined from AISI 8620 steel
- Full-auto M16 profile
- Heat treated and Carburized/strain relieved
- Precision ground gas key interface
- Gas key from 4130 steel, secured with staked Grade 8 fasteners
- Hard chrome-plated finish
Misc:
- Cam pin from 4340 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
Click here to browse our entire selection of Bolt Carrier Groups & Parts.
Logan B. (verified owner) –
An awesome bang for your buck BCG.
Maurice H. (verified owner) –
I have 3 and will never buy another type of BCG.
Mark H. (verified owner) –
This Microbest chrome plated BCG is a great deal. The quality of the machining is very good, especially on the bolt itself, and the chrome plating is excellent! I don’t have all the gauges to spec it out but I can say the gas rings are tight in the carrier bore and the carrier is a little tight when fully inserted into the brand new upper (an Aero m4E1), which to me implies tight machining tolerances. The inside of the carrier bore and the hammer engagement ramp are very smooth, and I was especially impressed with the clean and uniform radiusing on the lugs of the bolt.
I would like to add that I really appreciate the way Rooftop has plentiful stock of quality parts that are endlessly out-of-stock elsewhere (like this bolt carrier group and criterion barrels), and then top it off with great service and reasonable shipping options. This is a first rate outfitter!
Markus J. (verified owner) –
One of the few milspec+ carriers I run. The upgraded inserts is a nice touch and helps with mk18s or similar builds. Chrome is the coating I prefer on anything that is serious use. As always, Sol doesn’t fail to disappoint on shipping or prices. If he doesn’t have it, I wait until he does