CM15 338 ARC Semi Auto Rifle – 16″ FDE Metallic
The CM15 338 ARC Semi Auto Rifle brings the 338 ARC cartridge into Chattahoochee Munitions’ purpose-built AR-15 platform. This 16-inch configuration combines billet 7075-T6 receivers, a 1:8 twist barrel, adjustable gas and buffer systems, a low-mass bolt carrier group, and a TriggerTech AR15 Duty trigger.
This version features FDE Metallic Cerakote receivers and handguard with Coyote B5 Systems furniture. At approximately 6 pounds 10 ounces with an unloaded magazine and no accessories, the CM15 provides a conventional rifle-length semi-automatic configuration within the Chattahoochee Munitions 338 ARC family.
The CM15 is engineered as a complete gas-operated system. Chattahoochee Munitions equips the rifle with both a Superlative Arms adjustable gas block and an ODIN Works adjustable buffer, providing two points of adjustment within the operating system.
CM15 Billet Upper and Lower Receivers
The foundation of the 338 ARC Semi Auto Rifle is the CM15 billet receiver set. Both receivers are CNC machined from 7075-T6 aluminum and incorporate ambidextrous controls and a widely flared magazine well.
- AR-15-pattern receiver architecture
- CNC machined from 7075-T6 billet aluminum
- Pictogram-style Fire/Safe markings on both sides
- Lightened fire-control-group faces and magazine well
- Integral trigger guard
- Machined, widely flared magazine well
- Ambidextrous safety
- Ambidextrous magazine release
- Ambidextrous bolt release
- CM15 pivot and takedown pins
- FDE Metallic Cerakote
TriggerTech AR15 Duty Trigger
The CM15 uses the TriggerTech AR15 Duty trigger. Customers can select from three trigger configurations:
- Single-stage straight bow
- Single-stage curved bow
- Two-stage straight bow
These options allow the customer to choose between single-stage and two-stage operation while also providing straight- and curved-bow choices within the CM15 platform.
CM15 Low-Mass Bolt Carrier Group
The CM15 338 ARC Semi Auto Rifle uses a low-mass bolt carrier group built around a 9310 steel bolt. The bolt incorporates the requisite 6.5 Grendel Type II / .449″ bolt face for the CM15 338 ARC system.
- 9310 steel bolt
- 6.5 Grendel Type II / .449″ bolt face
- High Pressure Tested (HPT) bolt
- Magnetic Particle Inspected (MPI) bolt
- Nitride-coated bolt
- Nitride-coated carrier
- Nitride-coated gas key
- Hardened gas key
- Grade 8 hardened gas-key fasteners
- Staked gas key
- Tool-steel extractor
CM Ambidextrous Charging Handle
The CM15 is equipped with the CM Ambidextrous Charging Handle in collaboration with Breek Arms. Manufactured from 7075 aluminum, the charging handle provides ambidextrous operation and a robust interface for running the CM15 from either side of the rifle.
16″ 338 ARC Barrel – 1:8 Twist
The 16-inch 338 ARC Semi Auto Rifle uses a CrMV barrel with a black nitride finish and 1:8 twist rate. The barrel uses a pistol-length gas system with a .875-inch gas journal and is threaded 5/8×24 for compatible .338-caliber muzzle devices.
- 16″ barrel length
- CrMV steel
- Black nitride finish
- 1:8 twist rate
- Shouldered crown
- 5/8×24 muzzle threads
- .875″ gas journal
- Pistol-length gas system
Adjustable Gas and Buffer System
The CM15 uses an adjustable operating system rather than relying on a fixed gas-and-buffer combination. A Superlative Arms .875 adjustable gas block provides gas adjustment at the barrel.
At the rear of the system, the ODIN Works AR15 Lite Adjustable Buffer provides an additional tuning point at the receiver extension. Combined, these components provide adjustment at both ends of the operating system.
- Superlative Arms .875 adjustable gas block
- Melonite-treated pistol-length gas tube
- ODIN Works AR15 Lite Adjustable Buffer
- Adjustable buffer weight
- CM carbine receiver extension
- QD end plate
CM15 15″ M-LOK Handguard
The 16-inch CM15 uses the LWS low-profile 15-inch handguard finished in FDE Metallic Cerakote.
- 6061 aluminum construction
- 15″ length
- Dual-taper attachment system
- Steel barrel nut
- QD sling attachment points at 3 and 9 o’clock
- M-LOK mounting surfaces on sides and bottom
- Full-length Picatinny top rail
- FDE Metallic Cerakote
B5 Systems Furniture
Coyote B5 Systems furniture complements the FDE Metallic Cerakote finish.
- B5 Systems Bravo stock – Coyote
- B5 Systems pistol grip – Coyote
- B5 Systems rail covers – Coyote
- CM receiver extension – FDE Metallic Cerakote
- QD end plate
- ODIN Works AR15 Lite Adjustable Buffer
338 ARC Muzzle Device Options
The barrel uses 5/8×24 muzzle threads, allowing the rifle to be configured with compatible .338-caliber muzzle devices. Available configurations may include mounting solutions from Q, Dead Air, Yankee Hill, SilencerCo, and other compatible systems. Contact Chattahoochee Munitions regarding specific muzzle-device selections or price adjustments.
10-Round 338 ARC AR-15 Magazine
The 338 ARC Semi Auto Rifle includes a 10-round DURAMAG SS AR-15-pattern magazine vetted by Chattahoochee Munitions for 338 ARC. The magazine uses 410 stainless-steel construction and is selected as part of the complete CM15 operating system.
Additional magazines are available through the CM 338 ARC AR15 Magazine product page.
Why a 16″ 338 ARC Semi Auto Rifle?
The 16-inch CM15 serves a different role from CM’s shorter 338 ARC configurations. Chattahoochee Munitions testing of the loads we have evaluated indicates that powder utilization occurs largely around the 12-inch barrel-length range. The additional barrel length therefore is not simply an attempt to maximize velocity.
Instead, the 16-inch 338 ARC Semi Auto Rifle provides a conventional rifle configuration for customers who want the cartridge in a semi-automatic AR-15 platform without choosing an SBR or pistol configuration.
338 ARC in a Semi-Automatic AR-15 Platform
A defining characteristic of 338 ARC is its ability to place a .338-caliber cartridge within the AR-15 platform envelope. The CM15 is Chattahoochee Munitions’ semi-automatic implementation of that concept.
The combination of the requisite 6.5 Grendel Type II bolt face, compatible magazine, adjustable gas block, adjustable buffer, and purpose-built barrel creates a complete 338 ARC system rather than treating the cartridge as simply a barrel conversion.
For customers comparing CM platforms, the CM15 provides semi-automatic operation while the CM7S provides a manually operated bolt-action alternative. Both platforms can be explored through Containment Zone 338.
CM15 338 ARC Semi Auto Rifle Specifications
- Cartridge: 338 ARC
- Platform: CM15 / AR-15 pattern
- Operating system: Gas-operated semi-automatic
- Upper/lower: 7075-T6 billet aluminum
- Finish: FDE Metallic Cerakote
- Barrel: 16″ CrMV
- Barrel finish: Black nitride
- Twist: 1:8
- Muzzle thread: 5/8×24
- Gas journal: .875″
- Gas system: Pistol length
- Gas block: Superlative Arms .875 adjustable
- Buffer: ODIN Works AR15 Lite Adjustable Buffer
- Bolt: 9310 steel, HPT/MPI
- Bolt face: 6.5 Grendel Type II / .449″
- BCG: CM15 low-mass, nitride
- Charging handle: CM Ambidextrous Charging Handle in collaboration with Breek Arms
- Trigger: TriggerTech AR15 Duty
- Trigger options: Single-stage straight bow, single-stage curved bow, or two-stage straight bow
- Handguard: CM15 LWS 15″ M-LOK
- Stock: B5 Systems Bravo – Coyote
- Grip: B5 Systems – Coyote
- Magazine: 10-round DURAMAG SS, CM vetted for 338 ARC
- Weight: 6 lb 10 oz with unloaded magazine and no accessories
- Overall length: 33.25″–36.50″
- Length of pull: 11.50″–14.75″
Explore Containment Zone 338
Visit Containment Zone 338 to compare CM15 semi-automatic rifles, CM7S bolt-action systems, compact configurations, barreled actions, magazines, and technical information about 338 ARC.
338 ARC Semi Auto Rifle FAQ
Is the CM15 a semi-automatic 338 ARC rifle?
Yes. The CM15 is a gas-operated semi-automatic AR-15-pattern firearm chambered in 338 ARC.
What barrel does the 16-inch CM15 use?
The rifle uses a 16-inch CrMV barrel with a black nitride finish, 1:8 twist, pistol-length gas system, .875″ gas journal, and 5/8×24 muzzle threads.
What bolt face does the CM15 338 ARC use?
The CM15 uses a 9310 steel bolt with the requisite 6.5 Grendel Type II / .449″ bolt face. The bolt is High Pressure Tested and Magnetic Particle Inspected.
What trigger comes with the CM15?
The CM15 uses a TriggerTech AR15 Duty trigger. Customers can select a single-stage straight bow, single-stage curved bow, or two-stage straight bow configuration.
What charging handle does the CM15 use?
The rifle uses the CM Ambidextrous Charging Handle in collaboration with Breek Arms. It is manufactured from 7075 aluminum and provides ambidextrous operation.
Does the CM15 have an adjustable gas and buffer system?
Yes. The CM15 combines a Superlative Arms .875 adjustable gas block with an ODIN Works AR15 Lite Adjustable Buffer.
What magazine does the CM15 use?
The rifle includes a 10-round DURAMAG SS AR-15-pattern magazine vetted by Chattahoochee Munitions for 338 ARC.
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