BCM® MK2 Standard 12.5" 300 BLACKOUT Complete Upper Receiver Group w/ MCMR-10 Handguard

MSRP: $1,105.50
Your Price: $828.49
(You save $277.01 )
300 BLK
Barrel Length:
Barrel Style:
Upper Receiver:
Stock Status:

Out of stock

About the BCM® MK2 Standard 12.5" 300 BLACKOUT Complete Upper Receiver w/ MCMR-10 Handguard

  • Continuous taper barrel profile designed for optimal weight, balance, and performance.
  • Barrel profile fluted toward the rear near chamber area - Increases strength and heat dissipation.
  • Tapered barrel profile out front, for easier maneuverability.
  • No sharp handguard cap shoulder for improved barrel harmonics and improved accuracy.
  • Muzzle threaded in standard 30 cal (5/8x24).

Whats included with this complete upper:

  • Includes MCMR-10 Handguard
  • Includes MCMR-SM (MCMR Sling Mount)
  • Includes One 3" Picatinny Rail Section
  • Includes BCM® Comp Mod 1 - 762/300 BLK

Featuring BCM’s Patented MK2 Upper Receiver

This proprietary design offers enhanced rigidity over the USGI product.  The increased rigidity limits barrel deflection which aids in consistency/accuracy.   Less flex also reduces premature damage, wear, and failure of bolt lugs from misalignment.   A gas expansion chamber is machined above the charging handle track, combined with dual vents machined at the rear (each side, above charging handle latch) help to redirect and vent gas away the shooters face. U.S. Patent Numbers: 10670355, 10677549, D888182

BCM® has taken great care to ensure the best possible performance and interchangeability. However, due to the large operational range of 300 Blackout ammunition in the market place, BCM® cannot guarantee function will all ammunition types in all conditions. These barrels were designed to run with a H3 buffer with high velocity ammo. If running subsonic ammunition, it is recommended to run your suppressor and a carbine buffer. Fine tuning may be required in limited instances based on ammo and buffer choices that work best for the desired application. BCM® also recommends running the Crane O-ring (provided with all BCM® Bolt Carrier Groups) over the extractor with 300 Blackout.


  • Caliber: 300 Blackout
  • Barrel Length: 12.5"
  • Barrel Material: 11595E Spec Steel
  • Barrel Finish: Manganese Phosphate (Mil-Spec A-A-59267)
  • Bore & Chamber: Chrome Lined
  • Weight: 2.5 lbs
  • Twist Rate: 1:7
  • Gas System: Pistol
  • Muzzle Device: BCM® Comp Mod 1 (762/300BLK)
  • Muzzle Threads: 5/8x24
  • Handguard: MCMR-10

Shop Related Products:

Want to see more upper receivers? Click the links below to view more BCM® AR complete uppers!


Bravo Company builds: Life Saving Tools™
Copyright 2023 Bravo Company MFG, Inc.
***This product contains chemicals/materials known to the State of California to cause cancer and other reproductive harm. To learn more, visit www.p65warnings.ca.gov.***

9 Reviews

  • 5
    Great upper

    Great upper, awesome value. BCM quality is second to none.

  • 5
    Bcm 300blk 12.5in

    Fit and finish are amazing. Everything works and feels great. Love the little extra parts and stuff that are sent with the package. I have other ARs and none feel this good. Excellent shipping and fast customer service.

  • 5
    12.5 upper

    Love it!!

  • 5

    All around happy with this purchase. Insane craftsmanship for the price. Compared to what’s out there. Quick and easy shipping. Thing is super accurate and functions with no issues thus far. Would not hesitate to purchase another product or refer someone. Thanks guys.

  • 5
    Awesome upper.

    I had an issue with the receiver and bcm had me return it and got a fix out to me asap. Excellent upper with added features on the mk2

  • 5

    First BCM I've owned. Ordered after issues with Aero upper fulfillment. BCM was quick with fulfilling and shipping this order. Recieved the upper and went to the range save day. Held consistent and tight groups at 100 y.

  • 5
    BCM upper 12.5

    Great product

  • 5

    For a CT “other” build. I would have to say, as an owner of 7 ar15’s in multiple calibers, that don’t sit in a safe, that these are the best you’ll find in this price range. Plan on buying 3 more in next few weeks.

  • 5
    12.5 300 black out upper

    Absolute great craftsmanship and high quality as always from BCM. This 300 upper looks soo good with my spike lower. Can’t wait to get a can and shoot some subsonic and see how quite we can go!!