District 308 | 308 Winchester Rifles, Ammunition & Systems

CM7S Bolt-Action 308 Winchester Rifles

The CM7S Action

The CM7S is a steel, three-lug action on a Remington 700 footprint, so it accepts Remington 700-pattern triggers, bottom metal and chassis systems. Its main features:

• 60-degree bolt throw and an M16-style extractor
• One-piece, spiral-fluted bolt with a 0.718″ body diameter
• Wire EDM raceways for uniform tolerances and smooth cycling
• Pinned 20 MOA Picatinny rail and an integrated .300″ recoil lug
• .062″ firing pin to accommodate small-rifle-primer brass
• Tool-less fire-control removal and a side bolt-stop release
• 1-1/16″-16 barrel thread and a lightened 25 oz action body
• Full PVD coating for corrosion resistance and smoother operation

CM7S 308 barrels are 416R stainless steel with 5R rifling, a shouldered crown and 5/8×24 muzzle threads, mounted with a Remage-style barrel nut. Every CM7S uses a TriggerTech Rem 700 Primary set at approximately 1.5 lb, with a curved or straight shoe.

12.5″ Configurations: 1:5 Twist for Subsonic Hunting

The primary use of a short-barreled 308 is suppressed subsonic hunting, so CM’s 12.5″ CM7S barrels use a 1:5 twist. That twist stabilizes subsonic bullets of 220 grains and heavier, such as the 300-grain Maker REX in CM 308 subsonic ammo. Because a bolt action has no gas system, the same firearm also fires supersonic ammunition; CM recommends supersonic bullets of 160 grains and heavier in its 1:5 barrels. The 12.5″ CM7S is offered as a pistol or as an SBR, in the CM7 aluminum chassis or the WOOX walnut chassis.

16″ Configurations: 1:8 Twist for Supersonic Use

The 16″ CM7S rifles use a 1:8 twist, suited to supersonic ammunition and to subsonic loads of 220 grains and lighter. The 1:8 twist does not stabilize the 300-grain subsonic load. These are the CM7S 308 Winchester rifles to choose when range and supersonic energy matter more than a short overall length.

Chassis and Stock Options

• CM7 chassis: machined from a single block of billet aluminum, with a flared magazine well for AICS-pattern magazines, an ambidextrous magazine release, M-Lok, dual QD sling sockets, a full-length ARCA rail and a modular stock adapter. The 16″ CM7 configurations weigh 7 lb 4 oz.
• WOOX walnut chassis: a WOOX Exactus walnut stock with adjustable cheek riser and buttpad, a Furiosa walnut forend with M-Lok and M5 bottom metal for AICS-pattern magazines. It is heavier than the aluminum chassis, at 7 lb 12 oz in 12.5″ and 8 lb 10 oz in 16″.

Browse every CM7S 308 Winchester configuration.

CM10 Semi-Automatic 308 Winchester Rifles

Supersonic CM10 Configurations

The supersonic CM10 is offered as a 12.5″ pistol or SBR and as 16″ and 18″ rifles, all with 1:10 twist barrels. These 308 Winchester rifles are gassed for the pressure and volume of supersonic ammunition. They will not cycle subsonic loads.

Every CM10 uses receivers CNC machined from 7075-T6 billet aluminum, with no forward assist, ambidextrous safety, magazine release and bolt release, and a machined, flared magazine well. The upper carries a low-mass 9310 steel bolt carrier group, an ambidextrous charging handle, a Superlative Arms .750 adjustable gas block and an adjustable buffer. Barrels are 416R stainless steel with 5/8×24 muzzle threads. The trigger is a TriggerTech Duty set at approximately 3.5 lb, in your choice of straight, curved or two-stage straight. The 16″ configuration weighs 7 lb 4 oz with an unloaded magazine.

CM10 SUBSONIC

Most 308 AR10 rifles will not cycle subsonic ammunition. The CM10 SUBSONIC is a separate 12.5″ configuration with a 1:5 twist, developed by CM to cycle heavy subsonic 308 with an enclosed suppressor attached. It is offered as a pistol or SBR in Cobalt Kinetics Green, Black Tungsten or FDE Metallic.

The CM10 SUBSONIC has one firm limitation: supersonic ammunition in it is very problematic and potentially dangerous. If you want one semi-automatic for supersonic ammunition, choose a supersonic CM10 instead.

SR25 Pattern and Parts Compatibility

CM10 receivers are SR25 pattern and use high-profile handguards. That matters mainly if you are sourcing parts or accessories separately; complete CM10 308 Winchester rifles ship with the handguard, bolt carrier group and barrel already matched.

Browse every CM10 308 Winchester configuration.

Choosing Barrel Length and Twist for 308 Winchester Rifles

The table below summarizes how CM matches barrel length and twist across its 308 Winchester rifles, pistols and SBRs.

Configuration	Barrel	Twist	Primary load
CM7S pistol or SBR	12.5″	1:5	Subsonic 220gr and heavier; supersonic 160gr and heavier
CM7S rifle	16″	1:8	Supersonic; subsonic 220gr and lighter
CM10 SUBSONIC pistol or SBR	12.5″	1:5	Heavy subsonic only, with an enclosed suppressor
CM10 pistol or SBR	12.5″	1:10	Supersonic only
CM10 rifle	16″ or 18″	1:10	Supersonic only

Twist follows bullet weight. A 1:5 stabilizes subsonic bullets of 220 grains and heavier, and CM recommends supersonic bullets of 160 grains and heavier in it. A 1:8 stabilizes subsonic bullets of 220 grains and lighter, with no supersonic bullet-weight limitation. Barrel length follows the job: 12.5″ keeps a suppressed firearm compact, while 16″ and 18″ barrels give supersonic loads more velocity.

Suppressors on 308 Winchester Rifles

An enclosed suppressor traps gas in a sealed baffle stack and provides maximum suppression. A flow-through suppressor vents gas forward and outward, trading some suppression for lower back pressure.

• CM7S: an enclosed suppressor is the better choice for both subsonic and supersonic ammunition. With no gas system, back pressure has no effect on function.
• CM10 SUBSONIC: cycles heavy subsonic 308 with an enclosed suppressor attached.
• Supersonic CM10: a flow-through suppressor is the better match, because it keeps back pressure down on a firearm already gassed for supersonic pressure.

Suppressors are regulated under the National Firearms Act; follow all applicable federal, state and local requirements.

Ammunition for 308 Winchester Rifles

CM 308 subsonic ammunition loads the 300-grain Maker REX, a lead-free expanding bullet, in new Starline brass at a 1,005 fps average from a 12.5″ barrel. It requires a 1:5 twist and is intended for the CM7S 12.5″ configurations and the CM10 SUBSONIC.

For supersonic use, standard 308 Winchester factory ammunition runs in the CM7S 16″ and every supersonic CM10. In a CM7S 1:5 barrel, choose supersonic bullets of 160 grains and heavier. Never fire supersonic ammunition in a CM10 SUBSONIC, and never fire 300-grain subsonic ammunition in a 1:8 or 1:10 barrel.

Magazines for CM 308 Winchester Rifles

CM uses Magpul magazines on both platforms, and all of them feed CM’s 300-grain subsonic load.

• CM7S 308 Winchester 10-round magazine: Magpul AICS-pattern, for the CM7 and WOOX chassis
• CM10 308 Winchester 20-round magazine: Magpul PMAG
• CM10 308 Winchester 10-round magazine: Magpul PMAG

Pistols, SBRs and NFA Considerations

The 12.5″ CM7S and CM10 configurations are offered as a pistol or as a short-barreled rifle. A pistol configuration ships with a brace; an SBR configuration ships with a stock and is regulated under the National Firearms Act, which requires ATF approval before transfer. Stock-equipped short-barreled firearms are SBRs, not pistols. See NFA firearms for how CM handles NFA transfers, and follow all applicable federal, state and local requirements.

Explore District 308

Every one of the 308 Winchester rifles, pistols and SBRs in District 308 was chosen for a specific load and a specific job. Start with the ammunition you plan to shoot, then choose the platform, barrel length and twist that match it. Compare CM7S bolt-action 308 Winchester rifles and CM10 semi-automatic 308 Winchester rifles, or read the 308 subsonic vs supersonic guide first.