CM15 338 ARC 16″ AR15 Rifle – Black Tungsten Cerakote

Chattahoochee Munitions manufactures this 338 ARC AR15, a complete factory 16-inch CM15 AR15 rifle, with receivers and handguard finished in Black Tungsten Cerakote. It is chambered in 338 ARC with a 16-inch 416R stainless barrel and a 1:8 twist, an adjustable gas block and adjustable buffer for subsonic and supersonic ammunition, and a TriggerTech Duty trigger.

338 ARC puts a heavy .338-caliber bullet below the speed of sound in an AR15-size cartridge, and the CM15 is manufactured as a complete 338 ARC system from the factory: barrel, Type II bolt and magazine. See every configuration in Containment Zone 338, and read 338 ARC subsonic.

Why a 338 ARC AR15

A 338 ARC AR15 puts a heavy .338-caliber bullet into the familiar AR15 platform. With the right barrel, a Type II bolt and a 338 ARC magazine, the AR15 runs both the 307 gr subsonic and supersonic loads.

The 16-inch CM15 is the rifle-length option: it matches the SAAMI 16-inch test barrel and 1:8 twist, so it suits supersonic loads as well as subsonic, and needs no NFA registration.

CM15 Receivers and Bolt Carrier Group

The upper and lower are CNC-machined from 7075-T6 billet aluminum with ambidextrous controls. The CM15 low mass bolt carrier group uses a Type II spec 9310 steel bolt with the 6.5 Grendel Type II (.449-inch) bolt face, high-pressure tested and magnetic-particle inspected, with a nitride-coated bolt, carrier and gas key. The CM ambidextrous charging handle is made from 7075 aluminum in collaboration with Breek Arms.

Barrel, Gas and Buffer

The 16-inch barrel is 416R stainless steel with a 1:8 twist, finished in E100 Blackout Cerakote, with a shouldered crown and 5/8×24 muzzle threads. The 1:8 twist matches the SAAMI 16-inch test barrel and suits supersonic loads as well as the 307 gr subsonic. The pistol-length gas system uses a .875-inch gas journal and a Superlative Arms adjustable gas block, and an Odin Works adjustable buffer completes the tuning, so the CM15 can be set for subsonic or supersonic ammunition, suppressed or not. Read 338 ARC twist rate and 338 ARC barrel length.

Trigger, Handguard and Furniture

The TriggerTech AR15 Duty trigger breaks at 3.5 lb and comes single-stage straight, single-stage curved or two-stage straight. The CM15 LWS 15-inch M-LOK handguard is 6061 aluminum with a full-length Picatinny top rail. Furniture is from B5 Systems, in Black. The muzzle ships with an optional muzzle brake selection or a thread protector.

Ammunition and Magazine

The 338 ARC AR15 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 338 ARC AR15 magazine in 410 stainless steel, tested by Chattahoochee Munitions with 338 ARC. Standard 5.56 magazines do not feed the wider ARC case. Spares are available as the 338 ARC AR15 magazine.

Suppressing the CM15

With subsonic ammunition, Chattahoochee Munitions recommends an enclosed suppressor rated for .338 caliber or larger. With supersonic ammunition, a flow-through suppressor is recommended to limit back pressure. Use the adjustable gas block to tune for the suppressor you choose. Read the 338 ARC suppressor guide.

Black Tungsten Cerakote Finish

The receivers and handguard are finished in Black Tungsten Cerakote and the barrel in E100 Blackout Cerakote. Mechanical specifications match the Cobalt Kinetics Green Cerakote and FDE Metallic Cerakote models. Other lengths: 8.5-inch CM15 338 ARC, 10.5-inch CM15 338 ARC. For a bolt action, see the 12.5-inch CM7S 338 ARC and 338 ARC bolt action vs semi auto.

338 ARC AR15 Specifications

• Manufacturer: Chattahoochee Munitions
• Platform: CM15 AR15, gas operated semi-automatic
• Chambering: 338 ARC
• Configuration: Rifle
• Barrel: 16-inch 416R stainless steel
• Twist rate: 1:8
• Barrel finish: E100 Blackout Cerakote
• Muzzle: 5/8×24 threads, shouldered crown; optional muzzle brake selection or a thread protector
• Gas system: Pistol length, .875-inch gas journal, melonite-treated gas tube
• Gas block: Superlative Arms adjustable
• Buffer: Odin Works AR15 Lite adjustable
• Receivers: CNC-machined 7075-T6 billet aluminum, ambidextrous controls, Black Tungsten Cerakote
• Bolt carrier group: CM15 low mass, Type II spec 9310 steel bolt, 6.5 Grendel Type II (.449-inch) bolt face, nitride coated, HPT and MPI
• Charging handle: CM ambidextrous, 7075 aluminum, made in collaboration with Breek Arms
• Trigger: TriggerTech AR15 Duty, 3.5 lb, single-stage straight, single-stage curved or two-stage straight
• Handguard: CM15 LWS 15-inch M-LOK, 6061 aluminum, full-length Picatinny top rail, Black Tungsten Cerakote
• Furniture: B5 Systems (Black)
• Stock: B5 Systems Bravo
• Magazine: One 10-round 338 ARC AR15 magazine, 410 stainless steel, included
• Overall length: 33.25-36.50 inches
• Length of pull: 11.50-14.75 inches
• Weight: 6 lb 10 oz with an unloaded magazine and no accessories; the listing weight is for shipping

338 ARC AR15 FAQ

Who makes a 338 ARC AR15?

Chattahoochee Munitions manufactures this 16-inch CM15 338 ARC AR15, with a 416R 1:8 barrel, adjustable gas and buffer, and a TriggerTech Duty trigger. The CM15 338 ARC is also offered in 8.5, 10.5 and 16 inches, and as the CM7S bolt action.

Does it cycle subsonic 338 ARC?

Yes. The Superlative Arms adjustable gas block and Odin Works adjustable buffer let you tune the CM15 for subsonic or supersonic ammunition, suppressed or not.

What twist rate does it use?

A 1:8 twist in a 16-inch 416R stainless barrel.

What bolt does a 338 ARC AR15 need?

A bolt with the 6.5 Grendel Type II bolt face. The CM15 uses a Type II spec 9310 steel bolt in a low mass carrier.

What magazine is included?

One 10-round 338 ARC AR15 magazine in 410 stainless steel. Standard 5.56 magazines do not feed 338 ARC.

What trigger does the CM15 use?

The TriggerTech AR15 Duty at 3.5 lb, in single-stage straight, single-stage curved or two-stage straight.

What suppressor should I use on it?

An enclosed suppressor with subsonic ammunition; a flow-through suppressor with supersonic ammunition. Either must be rated for .338 caliber or larger. The barrel has 5/8×24 threads.

How much does the 16-inch CM15 338 ARC weigh?

6 lb 10 oz with an unloaded magazine and no accessories. Any heavier listing weight is the shipping weight.