5.56/300 Blackout Nitride MPI Full-Auto Profile Bolt Carrier Group

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Breek Arms is dedicated to using the right components for the most reliable functioning AR builds. The most important part in your AR15 is the bolt carrier group. This is why we’ve found a superior BCG with a high quality low friction nitride coating that protects against corrosion and heat that an AR15 endures over time. Each bolt carrier group under goes a magnetic particle inspection (MPI) to ensure you get a simple, no frill BCG that provides you with the reliability and performance you expect from a high end AR15. This BCG has the full-auto profile, but it will also perform perfectly in your semi-auto builds, and even in a full-auto build if you are lucky enough to have that opportunity.


  • New AR15 Bolt Carrier Group
  • Fully Assembled Bolt & Carrier Assembly
  • Caliber: .223/5.56 & 300AAC/Blackout
  • Carrier Steel: 8620
  • Carrier Finish: Nitride
  • Bolt Finish: Nitride
  • Bolt Steel: 9310
  • Profile: Full Auto Profile
  • Gas Key: 4140 Billet Gas Key with Grade 8 Hardened Fasteners, Staked per MilSpec
  • Bolt is Magnetic Particle Inspected (MPI)
  • Fastened with Grade 8 screws
  • Staked Per Mil-Spec
  • Firing pin machined from 17-4 H-900 Stainless Steel
  • Retaining pin 
  • Cam pin also 4140 with Nitride Finish
  • All Parts Made in the USA

13 Reviews Hide Reviews Show Reviews

  • 5

    Posted by Chris on May 3rd 2021

    I haven't used it yet but the finish and build is very nice, mpi,staked etc....

  • 5
    Nitride BCG

    Posted by Jim E Thomas on Apr 29th 2021

    I was delighted upon opening the envelope that arrived with the BCG inside. The BCG was inside a HD Plastic container like they keep large end mills so the edges do not touch anything that can dull the edges. First Class, Professional Packaging, and a very nice looking BCG. Finish was exceptional, even on the inside of the carrier and on the bolt. I am very happy with my purchase and can only say, "I wish I would have purchased 2!!"

  • 4
    Can't beat the price at this time

    Posted by Serge on Mar 16th 2021

    I bought this in combination warhammer which I got a couple of days ago and haven't had the chance to go to the range yet. The finish looks good and there are no fitment issues. As others have mentioned it looks just like the PSA which I also have and never had a problem with.

  • 5
    High quality BCG at a very low cost

    Posted by Warren Malig on Mar 10th 2021

    I’ve been on the hunt for a BCG for 3 months now to complete my build and it’s been difficult finding one due to them getting snatched up within minutes of being posted. I found this site and part thanks to a reddit group and after receiving it I can say that it is equivalent to or better than others i’ve seen that cost twice as much.

  • 5
    A Steal!

    Posted by Jonah Tyree on Jan 21st 2021

    I bought this for a budget AR I was building. When it arrived, it was pretty clear it was a PSA BCG, so it's cheaper but functional. Good finish, decent staking, ready to rock. What's really incredible is that Breek sells them cheaper than PSA. 10/10 would recommend for a budget gun.

  • 5
    300 blackout bcg

    Posted by John m. on Jan 13th 2021

    Super fast shipping Exactly what I ordered ordered a bcg and a t-shirt my favorite new shirt Great products will definitely order from breek arms again!!!!!