Chattahoochee Munitions manufactures this 338 ARC SBR, a complete factory 8-inch CM7S bolt action offered as a pistol with a telescoping Tailhook brace or as an SBR, with the chassis finished in FDE Metallic Cerakote. It is chambered in 338 ARC with an 8-inch Mos-Tek 416R stainless barrel, a 1:5 twist and a TriggerTech trigger, and it is made for suppressed subsonic shooting with the 307 gr subsonic bullet.
338 ARC puts a heavy .338-caliber bullet below the speed of sound in an AR15-size cartridge. The CM7S is manually operated, so it adds no action noise when suppressed and runs any subsonic load without tuning. See every configuration in Containment Zone 338, and read 338 ARC subsonic.
Why an 8-Inch 338 ARC SBR
A 338 ARC SBR on the 8-inch CM7S keeps a suppressed bolt action about the length of many unsuppressed rifles. It measures 20.5 inches overall collapsed and weighs 5 lb 12 oz.
The 1:5 twist spins the long 307 gr subsonic bullet 60 percent faster than the 1:8 SAAMI figure, and the bolt action adds no action noise when suppressed.
Pistol or SBR Configuration
This 338 ARC SBR can be ordered as a pistol with a telescoping Tailhook brace or as an SBR with a telescoping buttpad, each with an adjustable cheek riser and a 6.0 to 13.5-inch adjustment range. The CM Precision Vertical Crossover Grip, developed with MK Machining, positions the firing hand consistently. The SBR configuration is subject to National Firearms Act requirements and transfers through a licensed dealer; see NFA Firearms.
CM7S Action and Trigger
The CM7S action is steel with a Remington 700 footprint and a full PVD coating, about 25 oz. It has three locking lugs, a 60-degree throw and a one-piece spiral-fluted bolt with a .718-inch body, an M16-style extractor and a .062-inch firing pin. The bolt face is 6.5 Grendel Type II (.449 inch), matched to the ARC case head. An integrated .300-inch recoil lug and a pinned 20 MOA Picatinny rail complete the action. The TriggerTech Remington 700 Primary trigger comes curved or straight and adjusts from 1.5 to 4.0 lb.
Barrel and 1:5 Twist
The 8-inch barrel is made by Mos-Tek from 416R stainless steel with 5R rifling and a 1:5 twist, finished in E100 Blackout Cerakote, with a shouldered crown, 5/8×24 muzzle threads and Remage barrel-nut mounting. The 1:5 twist spins the long 307 gr subsonic bullet 60 percent faster than the 1:8 SAAMI figure, for stability from a short barrel. Read 338 ARC twist rate and 338 ARC barrel length.
Ammunition and Magazine
The 338 ARC SBR fires SAAMI 338 ARC factory ammunition, including the 307 gr Sub-X subsonic, which Hornady rates at 1,050 fps and 752 ft-lb from a 16-inch barrel, and 170 to 215 gr supersonic loads. Chattahoochee Munitions does not load 338 ARC ammunition. See 338 ARC ballistics.
It ships with one 10-round MDT polymer AICS-pattern magazine. MDT sells it as an ARC magazine, and Chattahoochee Munitions has tested it with 338 ARC. Spares are available as the 338 ARC bolt action magazine.
Suppressing the CM7S
Because the CM7S is a manually operated bolt action, Chattahoochee Munitions recommends an enclosed suppressor rated for .338 caliber or larger, with subsonic or supersonic ammunition. The bolt does not cycle when it fires, so the action adds no noise and nothing depends on gas pressure. The PLACID 375 is an enclosed suppressor rated from 5.56 NATO through .375. Read the 338 ARC suppressor guide.
FDE Metallic Cerakote Finish
The CM7 chassis is finished in FDE Metallic Cerakote, the barrel in E100 Blackout Cerakote, and the action carries a full PVD coating. Mechanical specifications match the Black Tungsten Cerakote and Cobalt Kinetics Green Cerakote models. Other lengths: 12.5-inch CM7S 338 ARC, 16-inch CM7S 338 ARC; or the walnut-stocked 12.5-inch CM7S. Compare platforms in 338 ARC bolt action vs semi auto.
338 ARC SBR Specifications
- Manufacturer: Chattahoochee Munitions
- Platform: CM7S bolt action
- Chambering: 338 ARC
- Configuration: Selectable pistol or SBR
- Barrel: 8-inch Mos-Tek 416R stainless steel, 5R rifling
- Twist rate: 1:5
- 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, three locking lugs, 60-degree throw, full PVD coating, about 25 oz
- Bolt: One-piece spiral-fluted, .718-inch body, 6.5 Grendel Type II (.449-inch) bolt face, M16-style extractor
- Firing pin: .062-inch
- Optic rail: Pinned 20 MOA Picatinny
- Trigger: TriggerTech Remington 700 Primary, curved or straight, adjustable 1.5-4.0 lb
- Chassis: CM7 billet aluminum, FDE Metallic Cerakote, flared magazine well, ambidextrous magazine release, full-length ARCA, M-LOK, dual QD
- Grip: CM Precision Vertical Crossover Grip
- Pistol rear: Telescoping Tailhook brace with adjustable cheek riser
- SBR rear: Telescoping buttpad with adjustable cheek riser
- Magazine: One 10-round MDT polymer AICS-pattern magazine included
- Overall length: 20.5-28.0 inches
- Length of pull: 6.0-13.5 inches
- Weight: 5 lb 12 oz, complete firearm; the listing weight is for shipping
338 ARC SBR FAQ
Who makes a 338 ARC SBR?
Chattahoochee Munitions manufactures this 8-inch CM7S 338 ARC SBR, offered as a pistol or SBR with a Mos-Tek 1:5 barrel and a TriggerTech trigger. The CM7S 338 ARC is also offered in 8, 12.5 and 16 inches and with walnut WOOX furniture, and as the CM15 AR15.
What twist rate does it use?
A 1:5 twist in an 8-inch Mos-Tek 416R stainless barrel with 5R rifling, to stabilize the long 307 gr subsonic bullet.
What ammunition does it use?
SAAMI 338 ARC factory ammunition, such as the 307 gr Sub-X subsonic and 170 to 215 gr supersonic loads.
What magazine does the CM7S 338 ARC use?
One 10-round MDT polymer AICS-pattern magazine is included, tested by Chattahoochee Munitions with 338 ARC.
What bolt face does the CM7S 338 ARC use?
The 6.5 Grendel Type II bolt face (.449 inch), which matches the ARC case head.
What is the difference between the pistol and SBR configuration?
The barrel, action and trigger are identical. The pistol uses a telescoping Tailhook brace and the SBR uses a telescoping buttpad, both with an adjustable cheek riser. The SBR is subject to National Firearms Act requirements.
What suppressor should I use on it?
An enclosed suppressor rated for .338 caliber or larger. The barrel has 5/8×24 threads.
How much does the 8-inch CM7S 338 ARC weigh?
The complete firearm weighs 5 lb 12 oz. Any heavier listing weight is the shipping weight.
Peter Wilson (verified owner) –