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Microbest AR15 5.56 C158 MPI Bolt Carrier Group, Complete

12 reviews Write a Review
MSRP: $134.95
You save $39.96
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2 units
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Microbest AR15 5.56 C158 MPI Bolt Carrier Group, Complete
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Microbest is one of the finest manufacturers of mil-spec bolt carrier groups for the military and small arms manufacturers. These are individually High Pressure Tested and then undergo a Magnetic Particle Inspection. We recommend degreasing and lubricating before installation. Ships in OEM packaging.

(All-Chrome with Phosphate Extractor can be found separately here.)


Nitride, Phosphate-Chrome or All-Chrome M-16 BCG

Mil Spec Carrier

  • 8620 Tool Steel
  • Full Auto M-16 cut

Mil-Spec Bolt

  • C158 Steel
  • Shot Peened
  • High Pressure Tested (HPT) 
  • Magnetic Particle Inspected (MPI)

Mil Spec Extractor

  • 4140 Steel
  • Sprinco Extractor Spring
  • Black Extractor Insert
  • Mil-Spec O-Ring

Mil Spec Gas Key

  • 4130 Steel
  • Grade 8 Hardware
  • Properly Staked

Weight: 11.6oz

Customer Reviews

12 reviews

  • 5

    Small problem, Arftac handled it

    This carrier seemed great. 7 7/16 length, good gas rings, clear gas path, good ejector spring tension, great firing pin protrusion (0.31), good coatings, good bolt support shoulder. The extractor spring and insert was crushed and bent upon inspection. Unsurprisingly, Arftac replaced them. Great carrier. Arftac rules

  • 5

    Micro best Chrome bolt carrier group

    Super clean piece from ARF tech No frills packaging but all frills product. Best price in the game let him know I have three dogs and he sent three treats that smelled so good I almost ate one.

  • 5

    Microbest AR15 5.56 C158 MPI Bolt Carrier Group

    Picked up numbers 3 and 4 of the all chromed BCG's The pricing and quality of these parts are hard to beat,plus these guys ship fast. What's not to like?

  • 5

    Best Value Microbest HPT/MPI BCG

    Take guy below review with a huge grain of salt. Anyone who knows about Microbest phosphate BCGs is that most, but not all, have the chrome overspray at front of carrier. Some don’t like BCM, but DD, SOLGW, Sionics, some batches of Centurion, and now this from arftac do have the that extra chrome on the front of the carrier. That is what tells you it’s Microbest without fancy packaging or engravings. What I received was clearly Microbest, and the cherry on top was that it already had a 5-coil Sprinco extractor spring. Aside from engraving, matches my DD, Sionics (minus OCKS), and unmarked MB from Charlie’s custom clones exactly. At $60-$120 less for same individually tested bolts used. Seriously, this is a no-brainer, and perfect to have as spares. If no packaging or engraving is problematic for you, please leave the rest of arftac’s stock for those of us who know better. Probably ordering another one just because.

  • 3

    Microbest BCG

    The vendor says it’s a Microbest, but there was no packaging, and no markings that identify the BCG. They said it is 158 carpenter steel, but is it really? How would you know? If I sell this BCG, how do I convince the buyer that this is a Microbest? From arftac: We ship in OEM packaging as the description says since Microbest is an OEM manufacturer. We will soon offer a branded product with markings for those that want it, but that will be more expensive and this was spec'ed to be a tremendous value in an unmarked, lifetime warranty BCG. We source these directly from Microbest if there's any question about that, and we take their word on the C158 as we do with every other vendor we source from when we spec certain features.

  • 5

    Microbest BCG

    Really, really nice fit and finish. Want to buy a second one now.

  • 5

    New BCG

    The BCG looks great. Surfaces look clean and staking looks great too. I haven’t had a range trip yet but I’m sure it’s good to go. I do hope the chrome extractor isn’t an issue but if it is I’m sure I can swap it for a phosphate extractor. Mostly I’m just very very pleased with the folks at arftac. Customer service is top notch, shipping was ridiculously fast especially for a holiday weekend, and I am so happy to know about arftac. Thank you. 10/10 recommended

  • 5

    Great BCG

    I already know how good Microbest BCG's are, which is why I bought it. But the real 5 stars goes to Arftac for great service, communication, and on-time fast shipping. Keep up the good work folks

  • 5

    Top Tier BCG

    Chrome finished BCG. Microbest is a top tier BCG. The chrome finish is easy to clean and strong. Easy install and after a headspace check and a lube, went to the range and put a couple hundred rounds down range with no issues.

  • 5

    Microbest phosphate

    The best bcg period!

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