CM7S 338 ARC Short Barrel Rifle – 8″ Cobalt Kinetics Green
The CM7S 338 ARC Short Barrel Rifle takes the Chattahoochee Munitions bolt-action platform into an exceptionally compact configuration. Built around an 8-inch MÔS-Tek 1:5 twist barrel, PVD-coated CM7S action, TriggerTech Primary trigger, and billet CM7 chassis, this firearm is designed for shooters who place a premium on compact overall dimensions and heavy .338-caliber capability.
At approximately 5 pounds 12 ounces and as little as 20.5 inches overall depending on configuration, this is the shortest complete CM7S in the 338 ARC family. It can be configured as a pistol with a telescoping Tailhook brace or as a Short Barreled Rifle with a telescoping buttpad.
Chattahoochee Munitions has extensive experience manufacturing and testing heavy .338-caliber firearm systems. The 8-inch configuration deliberately prioritizes compactness over the greater powder utilization available from our 12.5-inch and 16-inch barrels, creating a distinctly different option within the CM7S lineup.
CM7S Bolt Action – Full PVD Coating
The foundation of the 338 ARC Short Barrel Rifle is the Chattahoochee Munitions CM7S action. Built around the Remington 700 footprint, the CM7S incorporates features selected for precision, hunting, and demanding field use.
- Remington 700 footprint
- Three-lug bolt design
- 60-degree bolt throw
- M16-style extractor
- One-piece .718″ diameter bolt body
- Wire EDM raceways for consistent tolerances and smooth cycling
- Pinned 20 MOA Picatinny rail
- Large ejection port
- Lightweight action-body cutout
- .062″ firing pin
- Integrated .300″ recoil lug
- Tool-less fire-control removal
- Compatible with Remington 700-pattern triggers
- 1-1/16″-16 barrel thread
- Side bolt-stop release
- Oversize bolt knob
- Spiral-fluted bolt
- Full PVD coating
- 25 oz action weight
8″ MÔS-Tek 338 ARC Barrel – 1:5 Twist
The CM7S uses a MÔS-Tek custom bolt-action barrel manufactured from 416R stainless steel. Chattahoochee Munitions specifies a fast 1:5 twist rate throughout our CM7S 338 ARC firearm family.
- 8″ barrel length
- 416R stainless steel
- 5R rifling
- 1:5 twist rate
- Shouldered crown
- 5/8×24 muzzle threads
- Remage barrel-nut mounting system
- E100 Blackout Cerakote
Why Chattahoochee Munitions Uses a 1:5 Twist
The standardized 338 ARC specification uses 1:8 as a practical twist-rate baseline. Chattahoochee Munitions takes a different approach with the CM7S. Based on our experience manufacturing and testing heavy .338-caliber systems, including extensive work with 8.6 Blackout, we specify a 1:5 twist for our bolt-action 338 ARC barrels.
In Chattahoochee Munitions testing, the faster twist has performed particularly well with heavy .338-caliber projectiles such as the Hornady 307-grain Sub-X. This becomes especially relevant to the intended role of an extremely compact 338 ARC platform.
TriggerTech Remington 700 Primary Trigger
The 338 ARC Short Barrel Rifle is equipped with a TriggerTech Remington 700 Primary trigger. Flat and curved trigger options are available, with pull weight externally adjustable from approximately 1.5 to 4.0 pounds.
TriggerTech’s Frictionless Release Technology provides a crisp break and short overtravel. Hardened 440C stainless-steel internal components provide corrosion resistance and durability, while CLKR Technology provides defined pull-weight adjustment.
CM7 Billet Chassis – Cobalt Kinetics Green
The CM7 chassis provides a rigid aluminum foundation while allowing the 8-inch firearm to remain exceptionally compact.
- Machined from a single block of billet aluminum
- Flared magazine well for AICS-pattern magazines
- Ambidextrous magazine release
- AR-15 pistol-grip compatibility without an integrated dovetail
- Large trigger guard for gloved operation
- Modular single-bolt stock/brace adapter system
- M-LOK accessory mounting
- Dual integrated QD sling sockets
- Full-length bottom ARCA rail
- Cobalt Kinetics Green Cerakote
Pistol or SBR Configuration
The compact CM7S can be ordered in two configurations depending on the shooter’s intended application.
Pistol configuration: Telescoping Tailhook brace with adjustable cheek riser.
SBR configuration: Telescoping buttpad with adjustable cheek riser. Short Barreled Rifle configurations are subject to applicable federal, state, and local requirements and require transfer through an appropriately licensed dealer.
CM Precision Vertical Crossover Grip
The chassis is fitted with the CM Precision Vertical Crossover Grip, developed in collaboration with MK Machining. The near-vertical geometry complements the compact CM7S chassis and provides a natural interface across a variety of shooting positions.
10-Round AICS-Pattern Magazine
Each 338 ARC Short Barrel Rifle includes a 10-round MDT polymer 6 ARC AICS-pattern magazine. Chattahoochee Munitions has tested this magazine architecture with 22 ARC, 6 ARC, and 338 ARC in our bolt-action systems.
Why an 8″ 338 ARC?
The 8-inch CM7S exists for a different reason than its longer-barreled counterparts: compactness.
Based on Chattahoochee Munitions testing of the 338 ARC loads we have evaluated, powder utilization occurs largely around the 12-inch barrel-length range. Our 12.5-inch configuration is therefore the better choice when maximizing ballistic efficiency within a short package is the primary objective.
The 8-inch version deliberately moves farther toward the compact end of the spectrum. It gives up barrel length in exchange for a dramatically shorter firearm, reaching approximately 20.5 inches overall in its shortest configuration.
This distinction allows the 338 ARC Short Barrel Rifle to occupy its own role within the CM7S family rather than pretending every barrel length offers identical performance.
Built Around Heavy .338-Caliber Projectiles
338 ARC supports both subsonic and supersonic ammunition, but the compact CM7S architecture is particularly relevant to shooters interested in heavy .338-caliber projectiles and suppressed firearm systems.
The manually operated bolt action also separates the CM7S from a gas-operated AR-15. There is no requirement to use ammunition energy to cycle the action, allowing the firearm to function independently of the gas-system requirements associated with a semi-automatic platform.
CM7S 338 ARC Short Barrel Rifle Specifications
- Cartridge: 338 ARC
- Action: Chattahoochee Munitions CM7S
- Action footprint: Remington 700
- Bolt: Three-lug, 60-degree throw
- Bolt face: 6.5 Grendel Type II / .449″
- Barrel: 8″ MÔS-Tek 416R stainless steel
- Rifling: 5R
- Twist: 1:5
- Muzzle thread: 5/8×24
- Barrel finish: E100 Blackout Cerakote
- Trigger: TriggerTech Remington 700 Primary
- Trigger adjustment: 1.5–4.0 lb
- Chassis: CM7 billet aluminum
- Chassis finish: Cobalt Kinetics Green Cerakote
- Magazine: 10-round MDT polymer 6 ARC AICS-pattern magazine
- Weight: 5 lb 12 oz
- Overall length: 20.5″–28.0″
- Length of pull: 6.0″–13.5″
Explore Containment Zone 338
The 8-inch CM7S represents the compact end of the Chattahoochee Munitions 338 ARC family. Visit Containment Zone 338 to explore CM7S bolt-action firearms, CM15 AR-15 systems, barreled actions, magazines, and technical information about 338 ARC.
338 ARC Short Barrel Rifle FAQ
How long is the barrel on this CM7S?
This configuration uses an 8-inch MÔS-Tek 416R stainless-steel barrel with 5R rifling and a 1:5 twist.
Why does Chattahoochee Munitions use a 1:5 twist?
CM specifies the faster twist based on our testing and experience with heavy .338-caliber projectiles. In our testing, the 1:5 twist has performed particularly well with heavy projectiles such as the Hornady 307-grain Sub-X.
Why choose the 8-inch barrel instead of the 12.5-inch CM7S?
The primary advantage is compactness. Based on the loads CM has evaluated, the 12.5-inch configuration provides greater opportunity for powder utilization, while the 8-inch version prioritizes minimum overall length.
Can the 8-inch CM7S be configured as a pistol?
Yes. A pistol configuration with a telescoping Tailhook brace is available. The firearm can also be configured as an SBR with a telescoping buttpad, subject to applicable requirements.
What magazine does the CM7S use?
The firearm includes a 10-round MDT polymer 6 ARC AICS-pattern magazine that Chattahoochee Munitions has tested with 338 ARC in the CM7S platform.
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