M16 C158 5.56 Bolt Carrier Group - Black Nitride

Bexar Arms

MSRP: $189.99
Our Price: $179.99
(You save $10.00 )
(1 review) Write a Review

Out of Stock

As the main reciprocating component of the action, the Bolt Carrier Group is critical to the reliable function of your AR-15 or M16.

We take extreme care in making sure our BCG's are of the best quality possible for the most reliable function possible. Each BCG is individually gauged and inspected to ensure that all tolerances are met and exceeded. Because we gauge each BCG individually and hold extremely tight tolerances, we've chosen to use Helical Gas Rings for a more complete seal between the carrier and the bolt. Other manufacturers use carriers that were spec'd for chrome lining for their nitride carriers as well which leads to loose gas ring chambers, bolt tail seals, and bolt shoulder supports. We spec our nitrided carriers specifically to be nitrided, so our gas ring chamber, bolt tail seal, and bolt shoulder support is toleranced to account for the lack of a thick buildup of chrome. Our BCG will never fail the "gas ring test" with our Helical Gas Rings when new, guaranteed.

We install and dimple stake our gas keys in house to ensure that the gas key screws are torqued correctly, that the bottom of the gas key is flat, and that there's sealant used between the gas key and the carrier. We use OCKS screws for their improved design that accepts staking better than MilSpec screws which increase their resistance to backing out under harsh conditions. Permatex 27010 "Red Gel" is used to seal the gas key to the carrier as well as on the OCKS gas key screw threads to further resist loosening unintentionally.

All of these small improvements and attention to detail culminates into a BCG that is ready for anything you can put it through. If you're serious about quality, our BCG will not disappoint!


  • Individually Gauged and Inspected In House
  • Machined and Toleranced Specifically to be Nitrided
  • Compatible with 5.56, .223, 300 Blackout, 350 Legend, etc.
  • C158 Carpenter Steel Bolt
    • Black Nitrided
    • Shot Peened, Properly Heat Treated, and MPI Inspected
    • Inconel X750 Extractor Spring
    • Inconel X750 Ejector Spring
  • Billet Extractor
    • Billet 4140 Steel
    • Phosphated
    • Extractor Viton O-Ring included
  • 8620 Carrier
    • Back Nitrided
    • Full Auto M16 Profile
  • 4140 Billet Gas Key
    • Black Nitrided
    • Sealed to Carrier with Permatex 27010 "Red Gel"
    • "Decked" before Installation
    • Dimple Staked In House with OCKS Screws
  • 4140 Billet Cam Pin
    • Black Nitrided
  • Enhanced Helical Gas Rings
    • Guaranteed to pass the "Gas Ring Test" with our Carriers
  • Mil-Spec Firing Pin
    • Swiss Turned from 8640 Steel
    • Hard Chrome Plated
  • 100% Made in USA

1 Review Hide Reviews Show Reviews

  • 5
    Best Nitride Bolt Ive Ever Bought

    Posted by Patrick Huber on Dec 12th 2021

    Hey Guys I just wanted to let you all know how impressed I am with your BCG, and If I need another one or one of my friends do I'm sending them your way. Your BCG is better where it matters, the bolt is solid in the carrier, yours is the only bolt ive ever seen be able to pass the gas ring test with a helical gas ring and as far as I can remember you are the only one to keep a phosphated extractor when using a treatment like nitride on the rest of the bolt. It's really surprising that big names like BCM, Daniel Defense or SOLGW can ask so much money for what is essentially a rebranded Toolcraft or Microbest, no gauging, no gas key sealant, no improved gas key screws. I'm sure you are familiar with the SOTAR organization and his Youtube page, that kind of gauge work is how I found you guys on google, frankly I think this kind of attention to detail is something these big name brands lack entirely. Knights Armament totally sealed their gas block and tube, that's how important the best in the business thinks gas control is and I bet your bcg gauges better than theirs. I hope you guys release some fully chromed bcgs in the future, you'd give Young Manufacturing a run for their money for sure.