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CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly Up to 14% Off w/ Free Shipping — 4 models

CMMG, Inc CMM MC 4140CM .300 AAC Blackout, 8 in Medium Tapered Profile Barrel, 5/8-24 Threads, Salt Bath Nitride Finish, 30D810A
CMMG, Inc CMM Multi Role Profile Barrel Sub-Assembly 4140CM .300 AAC Blackout, 12.5in, 5/8-24 Threads, Salt Bath Nitride Finish, 30D8A0A
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A
CMMG, Inc MK4 MT 4140CM .300 AAC Blackout 16.1in Barrel Medium Taper Profile, 5/8-24 TPI, Salt Bath Nitride Finish, 30D120A
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A
CMMG, Inc CMM MC 4140CM .300 AAC Blackout, 8 in Medium Tapered Profile Barrel, 5/8-24 Threads, Salt Bath Nitride Finish, 30D810A
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CMMG, Inc CMM MC 4140CM .300 AAC Blackout, 8 in Medium Tapered Profile Barrel, 5/8-24 Threads, Salt Bath Nitride Finish, 30D810A
CMMG, Inc CMM Multi Role Profile Barrel Sub-Assembly 4140CM .300 AAC Blackout, 12.5in, 5/8-24 Threads, Salt Bath Nitride Finish, 30D8A0A
2 of 5 images
CMMG, Inc CMM Multi Role Profile Barrel Sub-Assembly 4140CM .300 AAC Blackout, 12.5in, 5/8-24 Threads, Salt Bath Nitride Finish, 30D8A0A
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A
3 of 5 images
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A
CMMG, Inc MK4 MT 4140CM .300 AAC Blackout 16.1in Barrel Medium Taper Profile, 5/8-24 TPI, Salt Bath Nitride Finish, 30D120A
4 of 5 images
CMMG, Inc MK4 MT 4140CM .300 AAC Blackout 16.1in Barrel Medium Taper Profile, 5/8-24 TPI, Salt Bath Nitride Finish, 30D120A
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A
5 of 5 images
CMMG, Inc 16in 300 ACC BLK, Carb Gas, 30DF80A

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Questions & Answers
Is this barrel dimpled? Expert Answer

The CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly does not have a dimpled barrel. This barrel has a 0.750" gas journal and utilizes M4 feed ramps. It is machined from 4140 chrome moly steel with a nitride finish.

by Ethan, Gear Expert, March 9, 2022
See 3 More Answers
What is the gas system length on the 12.5” Expert Answer

The 12.5" under MPN:30D8A0A is a pistol length gas system barrel.

by Armando R., Gear Expert, March 30, 2022
View All Q&A You Have a Question? Ask!
Customer Reviews
Helpful Positive Review
Great Barrel by JoePa, Verified Owner, January 13, 2021
I am using this in a pistol configuration. It is amazing. Using this barrel with a Yankee hill machine resonator and it functions flawlessly. Ran supersonic and subsonic ammunition without any problems.
7/8 found this helpful
Helpful Positive Review
CMMG 16" 300 BLK Barrel by Josh, Verified Owner, September 22, 2018
Awesome barrel that gives me the accuracy I need for my custom build. It can be difficult to find the sweet spot of accuracy vs cost when shopping for AR barrels but this one seems to have found it for me.
6/6 found this helpful
Helpful Positive Review
12.5" cmmg barrel by Russ, Verified Owner, November 12, 2021
As expected from CMMG. No rounds down yet. Note, this is a pistol length gas system. I double checked on cmmg's website. Optics planet is wrong. I already ordered carbine length and assembled it to the gas block. :-(
5/7 found this helpful
Helpful Negative Review
If buying for Subs, you will struggle by Al, Verified Owner, July 19, 2023
I purchased this barrel strictly for a 300 sub build. I know the optimal length is shorter, but I wanted to build a 16 inch sub build. Even with an adjustable gas block, I have yet to cycle rounds. It will run supers pretty well if you dial in the ga...
Read More...
2/5 found this helpful
Most Recent Reviews
12.5 cmmg barrel by MayorHaggar, Verified Owner, August 24, 2025
Fit properly and is accurate. No complaints with the product.
Most Recent Reviews
Thanks CMMG by Jetster, December 10, 2023
I am particularly fond of 12.5" battle rifles and when it comes to building them in 300 blk I always turn to CMMG and their 12.5 multi role barrel for the build. Quality that I am confident in when it is all on the line.
0/1 found this helpful
Read All 6 Reviews
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Product Info for CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly

Perfect for building your custom AR15 upper group. Comes with properly installed M4 barrel extension. All barrel sub-assemblies are properly headspaced.image

Features of CMMG, Inc 16inch 300 Acc Blkout 1:7 Carb Gas:

  • 16.1"
  • Multi Role Profile
  • 4140 Chrome Moly
  • Salt Bath Nitride Finish inside and out
  • 1:7 Twist
  • 300 AAC Blackout Chamber
  • Threaded 5/8-24
  • .750" Gas Journal

 

Specifications for CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly:

Manufacturer: CMMG
Color: Black
Finish: Salt Bath Nitride
Caliber: .300 AAC Blackout
Gun Model: AR-15
Condition: New
Firearms Threads Per Inch: 5/8x24

Package Contents:

  • CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly

CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly Orderable Models

List of Orderable Models

  • CMMG, Inc Barrel Sub-Assembly, Multi Role Profile, 300 BLK, 12.5in, 4140CM, Salt Bath Nitride, 30D8A0A , MPN: 30D8A0A , UPC: 815835062761 , Code: 2CM-ATB-CQASE-30D8A0A
  • CMMG, Inc Barrel Sub-Assembly, Mediun Taper Profile, 300 BLK, 8in, 4140CM, Salt Bath Nitride, 30D810A , MPN: 30D810A , UPC: 815835016283 , Code: 2CM-ATB-CQASE-30D810A
  • CMMG, Inc Barrel Sub-Assembly, Multi Role Profile, 300 BLK, 16.1in, 4140CM, Salt Bath Nitride, 30DF80A , MPN: 30DF80A , UPC: 815835011028 , Code: 2CM-ATB-CQASE-CQASE-EE
  • CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 4140CM, Salt Bath Nitride, 30D120A , MPN: 30D120A , UPC: 815835016238 , Code: 2CM-ATB-CQASE-30D120A

CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly Unavailable & Discontinued Models

List of Unorderable Models

  • USED, CMMG, Inc Barrel Sub-Assembly, Multi Role Profile, 300 BLK, 12.5in, 4140CM, Salt Bath Nitride, 30D8A0A , MPN: 30D8A0A-EDEMO , Code: 2CM-ATB-CQASE-30D8A0A-EDEMO-RE-C
  • DEMO, CMMG, Inc Barrel Sub-Assembly, Mediun Taper Profile, 300 BLK, 8in, 4140CM, Salt Bath Nitride, 30D810A , MPN: 30D810A-DEMO , Code: 2CM-ATB-CQASE-30D810A-DEMO
  • DEMO, CMMG, Inc Barrel Sub-Assembly, Multi Role Profile, 300 BLK, 12.5in, 4140CM, Salt Bath Nitride, 30D8A0A , MPN: 30D8A0A-DEMO , Code: 2CM-ATB-CQASE-30D8A0A-DEMO
  • DEMO, CMMG, Inc Barrel Sub-Assembly, Multi Role Profile, 300 BLK, 16.1in, 4140CM, Salt Bath Nitride, 30DF80A-DEMO , MPN: 30DF80A-DEMO , Code: 2CM-ATB-CQASE-CMMG30DF80A-DEMO
  • USED, CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 416SS, 30DC30A , MPN: 30DC30A-EDEMO , Code: 2CM-ATB-CQASE-30DC30A-EDEMO-WP-F
  • DEMO, CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 416SS, 30DC30A , MPN: 30DC30A-DEMO , Code: 2CM-ATB-CQASE-30DC30A-DEMO
  • CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 416SS, 30DC30A , MPN: 30DC30A , UPC: 815835016245 , Code: 2CM-ATB-CQASE-30DC30A
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