CM7S 338 ARC 12.5″ Barreled Action

Chattahoochee Munitions manufactures this 338 ARC short barreled action: a CM7S action with a 12.5-inch Mos-Tek 416R stainless barrel chambered in 338 ARC, a 1:6 twist and Remage barrel-nut mounting, ready for the stock or chassis, trigger and bottom metal you choose. The CM7S action uses the Remington 700 footprint, so it accepts Remington 700 pattern triggers and fits Remington 700 short-action pattern stocks and chassis.

338 ARC puts a heavy .338-caliber bullet below the speed of sound in an AR15-size cartridge, and the CM7S bolt action adds no action noise when suppressed. See every configuration in Containment Zone 338, and read 338 ARC subsonic.

Why a 12.5-Inch 338 ARC Short Barreled Action

A 12.5-inch 338 ARC short barreled action sits near the point where 338 ARC powder use is largely complete in Chattahoochee Munitions testing, so a suppressed bolt action stays compact with little subsonic velocity lost.

A 12.5-inch barrel on a firearm with a stock makes it a short-barreled rifle under the National Firearms Act, so complete the NFA paperwork before you assemble it as an SBR.

CM7S Action

The CM7S action is steel with a full PVD coating, about 25 oz, with wire EDM raceways, a large ejection port and a lightweight cutout. It has three locking lugs, a 60-degree throw, a one-piece spiral-fluted .718-inch bolt with an oversized knob, an M16-style extractor, a .062-inch firing pin and the 6.5 Grendel Type II (.449-inch) bolt face matched to the ARC case head. An integrated .300-inch recoil lug, a pinned 20 MOA Picatinny rail, tool-less fire-control removal and a side bolt-stop release complete it.

Barrel and 1:6 Twist

The 12.5-inch barrel is made by Mos-Tek from 416R stainless steel with 5R rifling and a 1:6 right-hand twist, finished in E100 Blackout Cerakote, with a shouldered crown and 5/8×24 muzzle threads. It mounts with the Remage barrel-nut system on 1-1/16-16 action threads. The 1:6 twist spins the long 307 gr subsonic bullet about a third faster than the 1:8 SAAMI figure, while still suiting supersonic loads. Read 338 ARC twist rate and 338 ARC barrel length.

What You Add

The barreled action includes the action, bolt, barrel, barrel nut and rail, about 57.4 oz together. You choose the stock or chassis, a Remington 700 pattern trigger such as the TriggerTech R700 Primary, bottom metal for AICS-pattern magazines, and a magazine. Chattahoochee Munitions uses the 10-round MDT polymer AICS-pattern 338 ARC bolt action magazine in its complete CM7S firearms. Have the completed firearm checked by a qualified gunsmith before firing.

For a complete factory firearm instead, see the 12.5-inch CM7S 338 ARC. Other barreled action lengths: 8-inch, 16-inch. For suppressor choice, read the 338 ARC suppressor guide: an enclosed suppressor rated for .338 caliber or larger is recommended on the bolt action.

338 ARC Short Barreled Action Specifications

• Manufacturer: Chattahoochee Munitions
• Type: CM7S barreled action
• Chambering: 338 ARC
• Barrel: 12.5-inch Mos-Tek 416R stainless steel, 5R rifling
• Twist rate: 1:6, right hand
• Barrel finish: E100 Blackout Cerakote
• Muzzle: 5/8×24 threads, shouldered crown
• Barrel mounting: Remage barrel nut, 1-1/16-16 action threads
• Action: Steel, Remington 700 footprint, full PVD coating, about 25 oz
• Bolt: Three lugs, 60-degree throw, one-piece spiral-fluted .718-inch body, 6.5 Grendel Type II (.449-inch) bolt face, M16-style extractor
• Recoil lug: Integrated, .300-inch
• Optic rail: Pinned 20 MOA Picatinny
• Weight: About 57.4 oz, barreled action; the listing weight is for shipping
• Not included: Stock or chassis, trigger, bottom metal, magazine

338 ARC Short Barreled Action FAQ

Who makes a 338 ARC short barreled action?

Chattahoochee Munitions manufactures CM7S 338 ARC barreled actions in 8, 12.5 and 16 inches with Mos-Tek barrels, plus complete CM7S 338 ARC firearms.

What does the barreled action include?

The CM7S action, bolt, barrel, Remage barrel nut and pinned 20 MOA rail. The stock or chassis, trigger, bottom metal and magazine are not included.

Will it fit Remington 700 stocks and triggers?

The CM7S uses the Remington 700 footprint, so it accepts Remington 700 pattern triggers and fits Remington 700 short-action pattern stocks and chassis. Confirm fit with the stock maker.

What twist rate does it use?

1:6 in a 12.5-inch Mos-Tek 416R stainless barrel with 5R rifling.

What bolt face does it have?

The 6.5 Grendel Type II (.449-inch) bolt face, matched to the 338 ARC case head.

What magazine should I use?

An AICS-pattern magazine made for the ARC case, such as the 10-round MDT polymer 338 ARC bolt action magazine, with AICS-compatible bottom metal.

What thread pitch is the muzzle?

5/8×24, with a shouldered crown.

How much does it weigh?

About 57.4 oz as a barreled action. Any heavier listing weight is the shipping weight.