CM7S 308 Subsonic Barreled Action
The CM7S 308 Subsonic Barreled Action combines CM’s Remington 700 short-action footprint with a 12.5-inch Mos-Tek barrel and fast 1:5 twist. The barrel is installed, headspaced and ready for a compatible Remington 700 short-action chassis or stock.
The 1:5 twist is selected for long, heavy subsonic projectiles, including the 300-grain Maker REX used in CM’s 308 subsonic ammunition. The manually operated action does not depend on ammunition pressure or suppressor backpressure to cycle, making it a strong foundation for a compact suppressed bolt-action firearm.
A trigger, chassis or stock, bottom metal and magazine are not included. The CM7S accepts compatible Remington 700-pattern triggers and fits Remington 700 short-action chassis or stock inlets that accommodate its integrated .300-inch recoil lug.
Explore CM’s complete family of 308 Winchester firearms, ammunition, magazines and technical guides in District 308.
What Is Included
- CM7S short action with bolt
- Full PVD coating on the action and bolt
- Pinned 20-MOA Picatinny optic rail
- Integrated .300-inch recoil lug
- 12.5-inch Mos-Tek 416R stainless steel barrel
- 1:5 twist with 5R rifling
- Installed and headspaced barrel
- Remage barrel nut
- 5/8×24 muzzle threads
- Thread protector
Not Included
- Trigger
- Chassis or stock
- Bottom metal
- Magazine
- Pistol brace or shoulder stock
- Suppressor or suppressor mount
- Optic or optic rings
NFA and Assembly Notice
This barreled action has a 12.5-inch barrel. Installing it in a chassis or stock with a shoulder stock creates a short-barreled rifle and requires the applicable NFA approval before assembly. Do not assemble a stocked configuration until the required approval has been received.
The serialized action is a firearm and must transfer through a licensed dealer. Review CM’s NFA firearms information and confirm all federal, state and local requirements before selecting or installing the remaining components.
CM7S Three-Lug Short Action
The CM7S action uses the established Remington 700 short-action footprint with a three-lug bolt and 60-degree throw. The reduced bolt rotation limits handle travel and provides additional clearance around the optic during operation.
A one-piece .718-inch bolt body, M16-style extractor and integrated .300-inch recoil lug form the mechanical foundation of the 308 Subsonic Barreled Action. Wire EDM-cut raceways establish uniform tolerances, while the oversized bolt knob and spiral-fluted bolt support smooth manual operation.
The action and bolt receive a full PVD coating for corrosion resistance and reduced operating friction. A pinned 20-MOA Picatinny rail provides a stable optic interface, while the large ejection port offers clear access to the chamber and action.
CM7S Action Specifications
- Footprint: Remington 700 short action
- Bolt design: Three lug
- Bolt throw: 60 degrees
- Extractor: M16 style
- Bolt construction: One piece
- Bolt-body diameter: .718 inch
- Bolt treatment: Spiral fluting
- Raceways: Wire EDM cut
- Optic rail: Pinned 20-MOA Picatinny
- Firing pin: .062 inch for compatibility with small-rifle-primer brass
- Recoil lug: Integrated .300 inch
- Fire-control removal: Tool-less
- Trigger compatibility: Remington 700 pattern
- Barrel thread: 1-1/16-inch-16
- Bolt stop: Side release
- Bolt knob: Oversized
- Action weight: Approximately 25 ounces
- Finish: Full PVD coating
Mos-Tek 12.5-Inch 1:5 Twist Barrel
The barrel is produced through CM’s collaboration with Mos-Tek. It is machined from 416R stainless steel, uses 5R rifling and receives E100 Blackout Cerakote for external protection.
The defining specification is its 1:5 twist. CM’s 300-grain Maker REX projectile measures 2.06 inches long and travels at approximately 1,005 feet per second from this barrel configuration. That combination of exceptional projectile length and subsonic velocity requires substantially more rotational speed than a conventional 1:8 or 1:10 twist barrel can provide.
The shouldered crown protects the muzzle, while 5/8×24 threads accept compatible direct-thread suppressors, suppressor mounts and muzzle devices. The barrel is installed with a Remage barrel nut.
Barrel Specifications
- Cartridge: 308 Winchester
- Barrel length: 12.5 inches
- Material: 416R stainless steel
- Rifling: 5R
- Twist rate: 1:5
- Crown: Shouldered
- Muzzle threads: 5/8×24
- Barrel attachment: Remage barrel nut
- Finish: E100 Blackout Cerakote
- Complete barreled-action weight: 57.4 ounces or 3.59 pounds
308 Winchester is standardized by the Sporting Arms and Ammunition Manufacturers’ Institute. Ammunition must still be matched to the barrel twist and intended use of the completed firearm.
Ammunition for the 1:5 Twist
The primary purpose of this 308 Subsonic Barreled Action is stabilizing heavy subsonic ammunition. CM recommends subsonic projectiles weighing 220 grains and heavier, including the 300-grain Maker REX used in CM 308 subsonic ammunition.
Because the firearm uses a manually operated action, the barrel can also fire appropriate supersonic 308 Winchester ammunition without requiring a gas system to cycle. CM recommends supersonic projectiles weighing 160 grains and heavier in this 1:5 twist configuration.
For lighter subsonic projectiles weighing 220 grains or less, or for a configuration primarily intended for conventional supersonic ammunition, the 16-inch 1:8 twist CM7S barreled action is the better match.
Read the 308 Winchester Subsonic Guide for the complete explanation of projectile length, velocity and stability.
Completing the Barreled Action
The CM7S uses the Remington 700 short-action footprint. A completed firearm requires a compatible trigger, chassis or stock, bottom metal and magazine.
- Chassis or stock: Remington 700 short-action inlet with clearance for the integrated .300-inch recoil lug
- Trigger: Compatible Remington 700-pattern trigger
- Bottom metal: Compatible with the selected chassis or stock and intended magazine system
- Magazine: Short-action AICS pattern when used with compatible bottom metal
The CM7S can use compatible polymer or metal short-action AICS magazines. The available 308 bolt-action magazine is a 10-round Magpul PMAG 7.62 AC capable of feeding CM’s 300-grain subsonic load.
When using a third-party chassis or stock, confirm Remington 700 short-action fit, recoil-lug clearance, trigger compatibility and magazine requirements with its manufacturer before ordering.
Suppressor Use
A bolt action does not use propellant gas to cycle, allowing the completed firearm to operate with or without a suppressor. CM generally recommends an enclosed suppressor because backpressure does not have to be balanced against semi-automatic bolt speed or receiver gas.
Subsonic ammunition removes the supersonic flight crack, while the suppressor reduces the muzzle report. The completed firearm is not silent; remaining sound includes the action, escaping gas and projectile impact.
The suppressor must be rated for 308 Winchester, the 12.5-inch barrel and the intended firing schedule. Confirm mounting compatibility, suppressor-to-bore alignment and manufacturer restrictions before firing.
Read the 308 Suppressor Guide for CM’s platform-specific recommendations.
308 Subsonic Barreled Action FAQ
What ammunition does CM recommend for this 1:5 twist barrel?
CM recommends subsonic projectiles weighing 220 grains and heavier, including its 300-grain Maker REX load. The barrel can also fire appropriate supersonic 308 Winchester ammunition; CM recommends supersonic projectiles weighing 160 grains and heavier in the 1:5 twist.
Does the barreled action include a trigger?
No. A trigger is not included. The action accepts compatible Remington 700-pattern triggers.
Will it fit a Remington 700 short-action chassis or stock?
The CM7S uses the Remington 700 short-action footprint with an integrated .300-inch recoil lug. Confirm that the selected chassis or stock provides the necessary recoil-lug clearance and supports the intended bottom metal and magazine system.
Does the barreled action require an FFL transfer?
Yes. The CM7S action is the serialized receiver, so the barreled action is a firearm and must transfer through a licensed dealer.
Can I install it in a chassis with a shoulder stock?
Not until the applicable NFA approval has been received. Installing this 12.5-inch barreled action in a shoulder-stocked configuration creates a short-barreled rifle. Confirm all applicable requirements before assembly.
Does it require a suppressor to function?
No. The manually operated action can fire compatible ammunition with or without a suppressor. An enclosed suppressor is recommended when maximum sound reduction is the priority.
Why Choose This 308 Subsonic Barreled Action?
Choose this 308 Subsonic Barreled Action when the completed firearm will prioritize compact dimensions, suppressed operation and heavy subsonic ammunition. It combines a Mos-Tek 12.5-inch 1:5 twist barrel with CM’s three-lug, 60-degree action, wire EDM-cut raceways, pinned optic rail and full PVD coating.
For conventional supersonic use or lighter subsonic projectiles, select the CM7S 16-inch 1:8 twist barreled action instead.
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