CM7S 8.6 Blackout 8″ Barreled Action

8.6 BLK Barreled Action | CM7S Compact 8″ Bolt Action

The CM7S 8.6 BLK Barreled Action combines the Chattahoochee Munitions CM7S action with an 8-inch barrel to create the most compact barreled-action configuration in the CM7S 8.6 Blackout lineup. It provides a foundation for customers who want to build their own short 8.6 Blackout bolt-action system while selecting the chassis, trigger, grip, magazine and rear configuration separately.

The CM7S uses a Remington 700 short-action footprint with a three-lug bolt, 60-degree throw, integrated recoil lug and pinned 20 MOA Picatinny rail. The 8-inch barrel is available with either a 1:3 or 1:5 twist, allowing the builder to select the barrel around the projectile and ammunition intended for the finished firearm.

Customers who want to complete the system with CM components can pair the barreled action with the CM7S Bolt Action Chassis, TriggerTech R700 Primary, Vertical Precision Crossover Grip and CM-vetted 8.6 Blackout Magazine.

CM7S Bolt Action

The action at the center of the 8.6 BLK Barreled Action is the same CM7S architecture used throughout the Chattahoochee Munitions bolt-action firearm family.

• Remington 700 short-action footprint
• Three-lug bolt design
• 60-degree bolt throw
• M16-style extractor
• One-piece .718″ bolt body
• Wire EDM raceways
• Pinned 20 MOA Picatinny rail
• Large ejection port
• Lightweight action-body cutout
• .062″ firing pin
• Integrated .300″ recoil lug
• Tool-less fire-control removal
• Accepts compatible Remington 700-style triggers
• 1-1/16″-16 barrel thread
• Side bolt-stop release
• Oversized bolt knob
• Spiral-fluted bolt
• Full PVD coating
• Action weight: 25 oz

The Remington 700 footprint provides access to a broad component ecosystem while also allowing the CM7S to be built around CM’s own chassis and supporting components.

8″ Mos-Tek 8.6 Blackout Barrel

The 8-inch barrel supplied with this 8.6 BLK Barreled Action is a Mos-Tek premium bolt-action barrel manufactured from 416R stainless steel with 5R rifling and finished in E100 Blackout Cerakote.

• 8″ barrel length
• 416R stainless steel
• 5R rifling
• Choice of 1:3 or 1:5 twist
• Shouldered crown
• 5/8×24 muzzle threads
• Remage barrel interface
• E100 Blackout Cerakote

CM offers both twist rates because projectile construction, length, weight, ammunition and velocity all influence stabilization. Neither twist should be treated as universally correct for every 8.6 Blackout configuration.

For more information about CM testing with barrel length, projectile weight, twist rate and suppression, read our 8.6 Blackout Subsonic Guide.

Why Choose an 8″ 8.6 BLK Barreled Action?

The defining advantage of the 8-inch 8.6 BLK Barreled Action is minimum host length. It is four inches shorter than our 12-inch version and eight inches shorter than the 16-inch configuration, giving the builder more control over the overall length of the finished firearm.

That difference becomes particularly useful when a suppressor will be added. Starting with an 8-inch barrel helps offset the additional length of the suppressor and allows the complete system to remain substantially shorter than one built around a conventional rifle-length barrel.

The shorter barrel is a deliberate configuration choice rather than a claim that 8 inches is universally optimal for 8.6 Blackout. In the subsonic loads CM has evaluated, powder utilization has been effectively complete at approximately 12 to 12.5 inches. The 8-inch configuration makes a different tradeoff by prioritizing minimum overall length.

Customers choosing between the 8-, 12- and 16-inch barreled actions should therefore consider the intended ammunition, projectile, twist rate, suppressor and desired overall firearm length together.

Choosing Between 1:3 and 1:5 Twist

The 8.6 BLK Barreled Action is available with either a 1:3 or 1:5 twist. CM offers both because twist selection should be based on the actual projectile and ammunition rather than the assumption that one twist is automatically best for every 8.6 Blackout load.

In CM testing with longer 12- to 12.5-inch configurations, 1:5 has generally stabilized projectiles around 300 grains or less well, while 1:3 has generally been better suited to heavy subsonic projectiles around 323 grains and above.

An 8-inch barrel changes the velocity environment, so those observations should not simply be transferred to every 8-inch load. Projectile construction, length, weight and actual velocity should all be considered when selecting the twist for this configuration.

Complete Your Compact CM7S Build

Starting with the CM7S 8.6 BLK Barreled Action gives the customer control over the remaining components of the firearm. CM offers the primary supporting components needed to build the barreled action into a complete CM7S-based system.

CM7S Bolt Action Chassis

The CM7S Bolt Action Chassis provides a purpose-built chassis option for the CM7S action. Its billet-aluminum construction incorporates an AICS-pattern magazine well, ambidextrous magazine release, M-LOK compatibility, integrated QD sling sockets and a full-length bottom ARCA rail.

TriggerTech R700 Primary

The CM7S accepts compatible Remington 700-style triggers. CM offers the TriggerTech R700 Primary for builders who want the same trigger family used in our complete CM7S firearms.

Vertical Precision Crossover Grip

The CM Vertical Precision Crossover Grip, developed in collaboration with MK Machining, can be paired with the CM7S chassis to complete the grip interface.

CM-Vetted 8.6 Blackout Magazine

Magazine selection is part of the complete 8.6 Blackout system. Rather than assuming every generic short-action AICS magazine will provide identical feeding, CM offers a vetted 8.6 Blackout Magazine for the CM7S platform.

Build the Complete System

The 8.6 BLK Barreled Action can serve as the starting point for a custom Remington 700-footprint build or be combined with CM components to create a firearm closely related to our complete CM7S configurations.

A straightforward CM build path includes:

• CM7S 8″ barreled action
• CM7S bolt-action chassis
• TriggerTech R700 Primary trigger
• CM Vertical Precision Crossover Grip
• CM-vetted 8.6 Blackout magazine

The builder can then select the appropriate rear configuration, optic, suppressor and other accessories around the intended application.

Customers who prefer to purchase a finished firearm can visit Area 8.6 to compare complete CM7S configurations, CM10 AR10 firearms and supporting 8.6 Blackout components.

Compact Suppressed Build Considerations

The 8-inch barrel terminates in 5/8×24 muzzle threads for compatible muzzle devices and suppressor mounting systems. Compatibility should always be verified for the specific suppressor, ammunition and firearm configuration.

The bolt-action operating system also removes the gas-system and buffer-system variables involved in cycling a semi-automatic firearm. Ammunition selection can therefore be approached independently from the requirements of a semi-automatic operating cycle.

For customers building around a suppressor, the short barrel is primarily about managing the overall dimensions of the finished system. The 8-inch 8.6 BLK Barreled Action provides the shortest starting point of the three CM7S barreled-action lengths.

CM7S 8″ 8.6 BLK Barreled Action Specifications

Platform	CM7S Bolt Action
Caliber	8.6 Blackout
Action Footprint	Remington 700 Short Action
Bolt	Three Lug, 60-Degree Throw
Action Finish	PVD
Optic Rail	Pinned 20 MOA Picatinny
Barrel Length	8″
Barrel Manufacturer	Mos-Tek
Barrel Material	416R Stainless Steel
Rifling	5R
Twist Rate	1:3 or 1:5
Muzzle Threads	5/8×24
Barrel Finish	E100 Blackout Cerakote
Barrel Interface	Remage
Trigger Compatibility	Remington 700 Pattern
Barreled Action Weight	49.21 oz / 3.07 lb

8.6 BLK Barreled Action FAQ

What is included with the 8″ 8.6 BLK Barreled Action?

The product combines the CM7S Remington 700-footprint action with an 8-inch 8.6 Blackout barrel. The chassis, trigger, grip and magazine can be selected separately to complete the firearm.

Can I complete the build with CM components?

Yes. CM offers the CM7S Chassis, TriggerTech R700 Primary, Vertical Precision Crossover Grip and vetted 8.6 Blackout Magazine.

Why choose the 8″ barrel?

The 8-inch configuration prioritizes minimum overall host length. This becomes particularly useful when a suppressor will add length to the finished firearm. Customers who prioritize additional barrel length should compare the 12- and 16-inch CM7S barreled actions.

Is 8″ the optimal barrel length for subsonic 8.6 Blackout?

Not necessarily. In the subsonic loads CM has evaluated, powder utilization has been effectively complete at approximately 12 to 12.5 inches. The 8-inch version makes a deliberate tradeoff by prioritizing a shorter overall system.

Should I choose a 1:3 or 1:5 twist?

The appropriate twist depends on projectile construction, length, weight, velocity and intended ammunition. Because the 8-inch barrel changes the velocity environment, twist selection should be made around the specific load rather than assuming one twist is universally correct.

Is the barrel suppressor compatible?

The barrel uses 5/8×24 muzzle threads for compatible muzzle devices and suppressor mounting systems. Compatibility should be verified with the specific suppressor and ammunition being used.

What magazine should I use?

The CM7S uses an AICS-pattern magazine architecture. CM offers a vetted 8.6 Blackout Magazine for the bolt-action platform.

Where can I compare the complete 8.6 Blackout lineup?

Visit Area 8.6 to compare complete CM7S firearms, CM10 AR10 platforms, barreled actions and supporting components.