BCM® MK2 Standard 9" 300 BLACKOUT Complete Upper Receiver Group w/ MCMR-8 Handguard

MSRP: $1,090.10
Your Price: $806.49
(You save $283.61 )
300 BLK
Barrel Length:
Barrel Style:
Upper Receiver:
Stock Status:

Out of stock

About the BCM® MK2 Standard 9" 300 BLACKOUT Complete Upper Receiver w/ MCMR-8 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)


  • MCMR-8 Handguard
  • MCMR-SM (MCMR Sling Mount)
  • One 3" Picatinny Rail SectionIncludes
  • 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.

Product details:

  • Caliber: 300 Blackout
  • Barrel Length: 9"
  • Barrel Material: 11595E Spec Steel
  • Barrel Finish: Manganese Phosphate (Mil-Spec A-A-59267)
  • Bore & Chamber: Chrome Lined
  • Weight: 2.2 lbs
  • Twist Rate: 1:7
  • Gas System: Pistol
  • Muzzle Device: BCM® Comp Mod 1 (762/300BLK)
  • Muzzle Threads: 5/8x24
  • Handguard: MCMR-8 

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


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***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.***

24 Reviews

  • 5
    Buy it

    Picked this up and dropped it on a Spikes lower receiver, fit very snug. I ran 200 rounds through it and got some nice groups at 50 yards and was on steel at 100 yards. H2 buffer and bcm bcg.

  • 5
    The best .300blk Upper

    I love this upper. It’s well built, light and handles great. I am a major BCM fan and this upper did not disappoint.

  • 5
    Short 300BLK that just runs

    I put together 150 rounds using the 147gr cheap plated bullets using the bottom of the load chart in my Hornady book (1200fps) - with H110 powder. Every one of them cycled just fine! I can't wait to get some heavier bullets and try some subs. I also ran 30 rounds of jacked bullets at (book speed) 1700fps and they cycle just fine too. Very happy with my 9" barrel 300BLK Mk2

  • 5
    Perfect Upper

    I’ve ran 110g up to 220g suppressed and unsuppressed with no issues. Light weight but very durable. I’ve always ran Daniel Defense Rifles I am now a BCM man.

  • 5
    BCM 9in 300 blk Upper

    Built like a tank these complete uppers are the best. I’ve beat the ever loving hell out of my BCM rifles and have never had a failure or rail come loose. They definitely have a place in the market where other rifle manufacturers fail

  • 5
    BCM® MK2 Standard 9" 300 BLACKOUT Upper Receiver Group w/ MCMR-8 Handguard

    Excellent all around. Customer service and products are top notch....more than satisfied keep up the great work.

  • 5
    BCM® MK2 Standard 9" 300 BLACKOUT Upper Receiver Group w/ MCMR-8 Handguard

    Awesome. Tight group with 300. Subs and supers works perfect.

  • 5


  • 5
    BCM 9 inch 300 blk out

    Battle Ready.... solid rail locked up tight. 3 moa barrel all day long. Shoots more accurate than me.