CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly | Up to 13% Off 4.7 Star Rating w/ Free Shipping

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 Barrel Sub-Assembly, 16.1in. MT 416SS, 300 BLK 30DC30A

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 Barrel Sub-Assembly, 16.1in. MT 416SS, 300 BLK 30DC30A

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

Show In Stock Only

5 Models Available

Color

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Barrel Length

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Barrel Profile

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Color:: Black
Barrel Length:: 8 in
Barrel Profile:: Medium Taper

Code: 2CM-ATB-CQASE-30D810A

MPN: 30D810A

UPC: 815835016283

List: ~~$199.95~~Save 13%

$173.49

Color:: Black
Barrel Length:: 12.5 in
Barrel Profile:: Multi Role

Code: 2CM-ATB-CQASE-30D8A0A

MPN: 30D8A0A

UPC: 815835062761

List: ~~$224.95~~Save 14%

$193.49

CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 416SS, 30DC30A

Color:: Silver
Barrel Length:: 16.1 in
Barrel Profile:: Medium Taper

Code: 2CM-ATB-CQASE-30DC30A

MPN: 30DC30A

UPC: 815835016245

List: ~~$204.95~~Save $10.96

$193.99

Color:: Black
Barrel Length:: 16.1 in
Barrel Profile:: Multi Role

Code: 2CM-ATB-CQASE-CQASE-EE

MPN: 30DF80A

UPC: 815835011028

List: ~~$224.95~~Save 13%

$195.49

Color:: Black
Barrel Length:: 16.1 in
Barrel Profile:: Medium Taper

Code: 2CM-ATB-CQASE-30D120A

MPN: 30D120A

UPC: 815835016238

List: ~~$224.95~~Save $4.96

$219.99

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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.

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
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

The CMMG, Inc 16inch 300 Acc Blkout 1:7 Carb Gas is a quality addition to the CMMG lineup. For more great deals on AR15 Barrels by CMMG, please browse our CMMG, Inc Gun Parts page.

What firearm models does the manufacturer say CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly is compatible with?

The manufacturer says that CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly is compatible with AR-15

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

List of Orderable Models

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, 12.5in, 4140CM, Salt Bath Nitride, 30D8A0A , MPN: 30D8A0A , UPC: 815835062761 , Code: 2CM-ATB-CQASE-30D8A0A
CMMG, Inc Barrel Sub-Assembly, Medium Taper, 300 BLK, 16.1in, 416SS, 30DC30A , MPN: 30DC30A , UPC: 815835016245 , Code: 2CM-ATB-CQASE-30DC30A
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

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CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly Up to 13% Off w/ Free Shipping — 5 models

Product Info for CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly

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

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

Package Contents:

What firearm models does the manufacturer say CMMG, Inc .300 AAC Blackout Barrel Sub-Assembly is compatible with?

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

List of Orderable Models

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

List of Unorderable Models