AR-15/M16 300 BLK BARRELS Reviews & Ratings

Direct replacement for the standard .223/5.56mm barrel converts your AR-15 to the high-performance 300 AAC Blackout (300BLK) cartridge. The 300 AAC lets you upgrade your rifle to 7.62 x 39 ballistics, while retaining the standard AR-15/M16 bolt, carrier, and magazine at its full capacity, with no additional modifications. 1-7" rifling accepts bullet weights from 110 gr to 220 gr, and 5/8"-24 muzzle threads accept popular AR-.308 flash suppressors and muzzle brakes. Three models available, 16", 12.5" and 8.2" long and treated inside and out with CMMG’s "Wasp" nitriding process for outstanding resistance to wear and corrosion. 16" barrel has the gas port in the standard position for use with all M4-length gas systems and supersonic ammunition. 12.5" & 8.2" barrels have the gas port positioned for use with pistol-length gas systems.

SPECS: Hardened 4140 chrome-moly steel, Wasp nitride finish, matte black .750" O.D. at gas port.5/8-24 muzzle threads.

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1 Stars

14%

Reviews Summary

Customers have mixed experiences with the AR-15/M16 300 BLK barrels. Many praise the accuracy and ease of installation, with a few indicating flawless performance. However, some encountered issues like dull crowns and headspace concerns. Customer service responses were mentioned positively, but repair timelines caused frustration. Overall, while quality control is variable, many were satisfied with the barrels' performance.

What Reviewers Are Saying

Product Quality

60%

The quality of the barrels received mixed reviews. While many customers were impressed with fit, finish, and performance, others experienced issues with crown cuts and headspacing, suggesting inconsistency in manufacturing quality.

Accuracy and Performance

70%

Many reviews highlight the barrels' accuracy as a standout feature, with users achieving impressive groupings even with various loads. Positive performance reports contribute to satisfaction, with some citing flawless operation during testing.

Customer Service

40%

Customer responses towards service were largely positive, with CMMG offering repairs for defective products. However, delays in repair times created frustration for some users who felt it negatively impacted their experience.

Installation and Compatibility

30%

Most users found installation straightforward, with parts aligning well. Issues were reported by a few regarding gas port alignment affecting the performance, indicating that precision during installation is critical.

Value for Money

45%

The affordability of the barrels impressed many reviewers, leading to a perception of good value for the performance received. Several customers noted they achieved competitive accuracy levels without breaking the bank.

Customer Photos & Videos

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Bad crowns

Really wanted to like these barrels due to the length and the "WASP" (nitride?) treatment which has claimed to be in the same ballpark of hardness/durability, without the inherent accuracy loss, of chrome lined barrels. Unfortunately both barrels I ordered (the initial first one, then a replacement) had the crowns cut on the same day with a dull tool. When the crown was cut the bit rolled inward, a "large" burr at the end of all of the lands. Big enough that dragging a dental pick across the lands it would come to a dead stop at the end where all the lands meet the crown. It also failed the Q-tip test. If this barrel was not WASP treated I probably would have rolled the dice and either tried to shoot out the burrs or break down and finally buy a good crowning tool setup because everything else was within spec. Emailed CMMG with some pictures and they immediately offered to fix the issue. Only problem was that "repair times are taking well beyond 6 working weeks to complete" (direct quote). Um, no thanks. I will utilize Brownell's awesome lifetime guarantee and just return them. Would have been pretty upset had this been an issue with a new complete rifle. If you have not purchased a Teslong bore scope (or any bore scope) yet I can't recommend one enough!! They are affordable and worth their weight in gold. I cringe when i think about how much time i would have wasted on my build, pulling my hair out, trying to figure out why the rifle wouldn't group. Brwonell's and Teslong for the win!

by NICHOLAS K. on May 15, 2024

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2 barrels will not head space

I was building a pair of rifles for friends. I have built 300 AAC rifles using the Brownells barrel with no issues. The fit and finish on these barrels looked great but they would not head space with the "go" gauge. I tried several bolts from several manufacturers including a well used Colt bolt. These chambers are way off!