CM10 8.6 Blackout Barrel – 16″ – AR10

8.6 Blackout AR10 Barrel | 16″ 416R Stainless

The Chattahoochee Munitions 8.6 Blackout AR10 Barrel is the 16-inch large-frame semi-automatic barrel configuration used in our CM10 8.6 Blackout platform. Manufactured from 416R stainless steel, this barrel features 1:3 twist rifling, M18x1.5 muzzle threads, a .875-inch gas-block journal and a carbine-length gas system.

CM has been building 8.6 Blackout firearms since the cartridge’s early introduction across both semi-automatic and bolt-action platforms. That experience has reinforced an important point: an AR10 barrel is only one part of the feeding and operating system. Barrel extension and receiver feed-ramp transition, magazine selection, gas regulation and buffer configuration all contribute to the finished firearm.

16″ 8.6 Blackout AR10 Barrel Specifications

• Barrel Length: 16″
• Material: 416R Stainless Steel
• Twist Rate: 1:3
• Muzzle Threads: M18x1.5
• Gas System: Carbine Length
• Gas Block Journal: .875″
• Crown: Shouldered Crown
• CM Application: CM10 8.6 Blackout

16″ Barrel Length for 8.6 Blackout

The 16-inch 8.6 Blackout AR10 Barrel provides a full-length rifle configuration for customers who do not want to build around a short barrel. Within the CM10 lineup, it is the longest of our current 8.6 Blackout semi-automatic barrel configurations.

For subsonic use, additional barrel length should not automatically be interpreted as additional efficiency. In the subsonic loads CM has evaluated, powder utilization has been effectively complete at approximately 12 to 12.5 inches. The 16-inch barrel instead provides a conventional rifle-length configuration while retaining the other characteristics of the CM10 operating system.

For more information about CM’s first-party experience with barrel length, projectile weight, twist rate and suppressed configurations, read our 8.6 Blackout Subsonic Guide.

1:3 Twist 8.6 Blackout Barrel

This 8.6 Blackout AR10 Barrel uses a 1:3 twist rate. CM also uses different twist configurations elsewhere in our 8.6 Blackout firearm lineup because projectile construction, length, weight and velocity influence stabilization.

The 1:3 twist option is particularly relevant when configuring an 8.6 Blackout system around heavier projectiles. CM’s testing with 12.5-inch and longer barrels has generally shown better stabilization of heavy subsonic projectiles in the approximately 323-grain-and-heavier range with 1:3 twist. Individual projectile construction, ammunition and velocity remain important variables.

M18x1.5 Muzzle Threads

The barrel uses M18x1.5 muzzle threads, providing the muzzle interface used throughout CM’s semi-automatic 8.6 Blackout barrel configurations. Customers should select a muzzle device or suppressor mounting system with the appropriate thread specification and compatibility for their intended configuration.

Carbine-Length Gas System

The 16-inch barrel uses a carbine-length gas system with a .875-inch gas-block journal. In complete CM10 firearms, Chattahoochee Munitions pairs the barrel with an adjustable gas block and adjustable buffer system so the operating system can be configured around ammunition and suppressed use.

CM complete firearms use a Superlative Arms .875 Adjustable Gas Block together with an ODIN Works AR10 Adjustable Buffer.

Feed-Ramp Fitting Is Important

This barrel should not be assumed to be a drop-in component for every large-frame receiver.

Chattahoochee Munitions is a firearm manufacturer, and during assembly of our complete CM10 firearms we perform finishing work at the feed-ramp interface to create a smooth transition between the receiver and barrel extension for the large .338-caliber projectiles used by 8.6 Blackout.

When this 8.6 Blackout AR10 Barrel is installed into a different receiver, the receiver and barrel-extension feed ramps may require inspection, fitting or finishing work during assembly. Component tolerances and feed-ramp alignment can vary between large-frame receivers.

If you are not familiar with evaluating and fitting the feed-ramp transition on a large-frame semi-automatic firearm, CM recommends having the installation evaluated by a qualified gunsmith or purchasing a complete CM10 firearm in which this work has already been performed during assembly.

Designed Around the CM10 Platform

The barrel is used within CM’s conventional SR25-pattern CM10 architecture. Our complete 8.6 Blackout firearms combine the barrel with vetted magazines, customized feed ramps, adjustable gas and adjustable buffer weight.

This system-level approach is why a complete CM10 should not be viewed simply as an AR10 assembled around an 8.6 Blackout barrel. The individual components are selected and configured to work together around the cartridge.

8.6 Blackout Magazine Selection

The CM10 uses conventional SR25-pattern magazines. Chattahoochee Munitions offers both compact 10-round and higher-capacity 20-round magazine options that we use and vet with the CM10 8.6 Blackout platform.

For additional capacity, see the CM10 20-Round 8.6 Blackout Magazine.

8.6 Blackout AR10 Barrel Specifications

8.6 Blackout AR10 Barrel FAQ

What twist rate does this 8.6 Blackout barrel use?

This 16-inch 8.6 Blackout AR10 Barrel uses a 1:3 twist rate.

What muzzle thread does the barrel use?

The barrel is threaded M18x1.5.

What gas system does the 16-inch barrel use?

This barrel uses a carbine-length gas system with a .875-inch gas-block journal.

Is this barrel a drop-in component for every AR10 receiver?

No. Large-frame component dimensions and feed-ramp alignment can vary. CM performs finishing work at the receiver and barrel-extension feed-ramp transition during assembly of our complete firearms. A barrel installed into another receiver may require inspection, fitting or finishing work.

Why does CM perform feed-ramp finishing?

CM10 8.6 Blackout firearms feed large .338-caliber projectiles. During firearm assembly, CM evaluates and finishes the transition between the receiver and barrel extension as necessary to create the appropriate feed path for the completed firearm.

Does CM offer complete 8.6 Blackout AR10 firearms?

Yes. CM offers complete CM10 8.6 Blackout firearms in multiple barrel lengths and configurations. Complete firearms incorporate the barrel, vetted magazine, customized feed-ramp transition and adjustable operating system as a coordinated package.

Where can I see the complete CM 8.6 Blackout lineup?

Visit Area 8.6 to compare CM10 semi-automatic firearms, CM7S bolt-action firearms, barreled actions, magazines and other 8.6 Blackout products.