Chattahoochee Munitions manufactures CM15 AR15 rifles, pistols and SBRs in eight cartridges: 300 Blackout, 338 ARC, 5.56 NATO, 6mm ARC, 22 ARC, 6.5 Grendel, 350 Legend and 400 Legend. The CM15 comes as 5 to 10.5-inch pistols or SBRs, as the CM15-SD 300 Blackout with part of the suppressor inside the handguard, and as 16 to 20-inch AR15 rifles, all on 7075-T6 billet receivers. Chattahoochee Munitions also sells complete CM15 uppers in ten cartridges, including 458 SOCOM, 450 Bushmaster and 12.7x42mm, and magazines for every CM15 cartridge.
The CM15 is a short-barrel subsonic semi-auto first. Subsonic 300 Blackout and 338 ARC run in 5 to 10.5-inch CM15 pistols and SBRs with 1:5 twist barrels for heavy bullets, and an adjustable gas block and buffer tune each one to cycle with an enclosed suppressor. The same platform then carries 5.56 NATO for low-cost training and the ARC family, 6.5 Grendel and the Legend cartridges in 16 to 20-inch AR15 rifles for hunting, predators and reach.
What Is the CM15?
The CM15 is the Chattahoochee Munitions AR15, a gas-operated semi-automatic on standard AR15 architecture. Each one pairs CNC-machined 7075-T6 billet receivers with a Superlative Arms adjustable gas block, an adjustable AR15 buffer, the CM15 Low Mass bolt carrier group and a TriggerTech Duty trigger, so the gas system can be set for the ammunition and suppressor you actually use.
CM15 AR15 Specifications
- Receivers: 7075-T6 billet aluminum upper and lower, CNC machined, integral trigger guard, flared magazine well; complete CM15 uppers use a lightweight 6061 billet upper receiver
- Controls: ambidextrous safety, magazine release and bolt release, and the CM15 ambidextrous 7075 charging handle made in collaboration with Breek Arms
- Bolt carrier group: CM15 Low Mass with a 9310 steel bolt, high-pressure tested and magnetic particle inspected, nitride finish; a Type II (6.5 Grendel) bolt face on 6.5 Grendel, 6mm ARC, 22 ARC and 338 ARC
- Gas and buffer: Superlative Arms adjustable gas block, ODIN Works adjustable AR15 buffer; micro, pistol, carbine, midlength or rifle-length gas set per cartridge and barrel length
- Barrels: 416R stainless steel in E100 Blackout Cerakote on 22 ARC, 6mm ARC, 6.5 Grendel and 338 ARC; 416R stainless, black nitrided, on 400 Legend; nitrided chrome-moly-vanadium steel on 5.56 NATO, 300 Blackout and 350 Legend
- Twist: set per cartridge, from 1:5 (short 300 Blackout and 338 ARC) to 1:16 (350 Legend and 400 Legend); see the lineup table below
- Trigger: TriggerTech AR15 Duty, single-stage straight, single-stage curved or two-stage straight, 3.5 lb
- Handguard: CM15 LWS M-LOK from 4 to 15 inches with QD sockets and a full Picatinny top rail, SLR Rifleworks ZRO on the 10.5-inch 300 Blackout, and the SLR Rifleworks SD ZRO on the CM15-SD
- Furniture: B5 Systems Bravo stock and grip on rifles and SBRs, or a telescoping brace on pistols
- Magazines: one magazine ships with each CM15: a 30-round ETS on 5.56 NATO and 300 Blackout, and a 10-round magazine on 338 ARC, 6mm ARC, 22 ARC, 6.5 Grendel, 350 Legend and 400 Legend
- Muzzle: threaded for the cartridge, with optional muzzle brake selection or a thread protector
- Weight: 5 lb 10 oz (5-inch 300 Blackout) to 7 lb 4 oz (20-inch 22 ARC and 6.5 Grendel) with an unloaded magazine; listing weights are shipping weights
- Finishes: Black Tungsten Cerakote with black furniture, or Cobalt Kinetics Green Cerakote or FDE Metallic Cerakote with Coyote furniture; the CM15-SD is color selectable
- Manuals: the CM15 and CM10 safety manual is on the Manuals page
CM15 AR15 Rifles, Pistols and SBRs
Every short CM15 can be ordered as a pistol or an SBR. The barrel, receivers and trigger are identical; the pistol uses a telescoping brace and the SBR uses a B5 Systems Bravo stock. An SBR is regulated under the National Firearms Act (see NFA Firearms), and the 16 to 20-inch CM15 AR15 rifles need no NFA paperwork.
- 5-inch pistol or SBR: 300 Blackout with micro-length gas, 5 lb 10 oz
- 7.5 and 8-inch pistol or SBR: 300 Blackout at 7.5 inches and 5.56 NATO at 8 inches, 6 lb
- 8.5-inch pistol or SBR: 338 ARC, 5 lb 14 oz
- 10.5-inch pistol or SBR: 300 Blackout, 338 ARC and 5.56 NATO, 6 lb 4 oz to 6 lb 10 oz
- CM15-SD 300 Blackout: 5, 7.5 and 10.5-inch pistols or SBRs with an SD handguard that surrounds part of an enclosed suppressor, including the 300 Blackout Tucked Suppressor and 300 Blackout PDW
- 16-inch rifle: 300 Blackout (1:7, for supersonic and subsonic), 338 ARC, 5.56 NATO, 6mm ARC, 22 ARC, 6.5 Grendel and 400 Legend, 6 lb 6 oz to 6 lb 14 oz
- 18-inch rifle: 6mm ARC, 22 ARC, 6.5 Grendel and 350 Legend, 6 lb 12 oz to 6 lb 14 oz
- 20-inch rifle: 22 ARC and 6.5 Grendel, 7 lb 4 oz
Shop every configuration in the CM15 category.
CM15 Cartridge Lineup
Every cartridge offered in CM15 AR15 rifles has its own hub with ballistics, barrel length, twist rate and hunting guides. Use this table to compare them, then follow the hub link for the details or the shop link for the firearms.
| Cartridge | CM15 barrel lengths | Twist | Subsonic | Cartridge hub | Shop |
|---|---|---|---|---|---|
| 300 Blackout | 5, 7.5 and 10.5 inches (also CM15-SD); 16 inches | 1:5; 1:7 on the 16-inch | Yes, 5 to 10.5 inches | Sector 300 | CM15 300 Blackout |
| 338 ARC | 8.5, 10.5 and 16 inches | 1:5; 1:8 on the 16-inch | Yes, 307 gr | Containment Zone 338 | CM15 338 ARC |
| 5.56 NATO | 8, 10.5 and 16 inches | 1:7 | No | Garrison 5.56 | CM15 5.56 NATO |
| 6mm ARC | 16 and 18 inches | 1:7 | No | Overwatch 6 | CM15 6mm ARC |
| 22 ARC | 16, 18 and 20 inches | 1:7 | No | Flight Deck 22 | CM15 22 ARC |
| 6.5 Grendel | 16, 18 and 20 inches | 1:8 | No | Grendel’s Lair | CM15 6.5 Grendel |
| 350 Legend | 18 inches | 1:16 | No | Hall of Legends | CM15 350 Legend |
| 400 Legend | 16 inches | 1:16 | No | Hall of Legends | CM15 400 Legend |
The 6mm ARC is often shortened to 6 ARC. The 6mm ARC and 22 ARC are both derived from the 6.5 Grendel case, which is why all three, and the 338 ARC, share the Type II bolt face.
Why AR15 Rifles for Short-Barrel Subsonic
A subsonic bullet travels below the speed of sound, so it makes no supersonic crack, and a suppressor then reduces the muzzle blast. The 300 Blackout and 338 ARC were designed to fit the AR15 magazine with heavy bullets, so a standard-size AR15 can run them subsonic without the weight of a large frame. The 1:5 twist on the short CM15 barrels stabilizes those long, heavy subsonic bullets.
A semi-automatic also needs enough gas to cycle its bolt carrier, and a subsonic load makes far less gas than a supersonic one. The CM15 answers that with an adjustable gas block, an adjustable buffer and the CM15 Low Mass bolt carrier group, so it can be tuned to cycle the load with the suppressor attached. Heavy subsonic bullets also finish burning their powder early, which is why Chattahoochee Munitions recommends 10 to 10.5 inches as a general-purpose 300 Blackout length. Read 300 Blackout subsonic, 300 Blackout gas system and 338 ARC subsonic.
The CM15-SD 300 Blackout takes that one step further. Its SD handguard surrounds the rear of an enclosed suppressor, so the suppressed firearm is shorter than a conventional CM15 of the same barrel length.
Choosing CM15 AR15 Rifles by Use
- Suppressed subsonic shooting: 300 Blackout in 5 to 10.5 inches, including the CM15-SD, and 338 ARC in 8.5 and 10.5 inches.
- Deer: 300 Blackout, 338 ARC, 6.5 Grendel, 6mm ARC, 350 Legend and 400 Legend, with expanding hunting bullets. For deer, step up from 5.56 NATO to one of these.
- Hogs: 300 Blackout, 338 ARC, 350 Legend and 400 Legend, or 6.5 Grendel and 6mm ARC as a step up from 5.56 NATO.
- Bear: the 400 Legend is bear-capable for black bear. For brown and grizzly bear, Chattahoochee Munitions recommends the 375 Raptor or 458 SOCOM XL in the CM7S or CM10.
- Coyotes and predators: 22 ARC, 6mm ARC, 6.5 Grendel and 5.56 NATO in 16 to 20-inch AR15 rifles; read the predator hunting cartridges guide.
- Home defense: a 10.5-inch CM15, with 5.56 NATO or subsonic 300 Blackout, which is quieter suppressed and carries less velocity past the target.
- Targets and training: 5.56 NATO is a low-cost target and training round, and the same CM15 controls carry over when you step up to another cartridge.
- Reach and precision: the 18 and 20-inch 22 ARC, 6mm ARC and 6.5 Grendel with supersonic ammunition.
CM7S vs CM10 vs CM15
Chattahoochee Munitions manufactures three platforms. The CM7S is the bolt action; the CM10 and CM15 are gas-operated semi-automatics.
| CM7S | CM10 | CM15 | |
|---|---|---|---|
| Type | Bolt action | Large-frame semi-auto (AR10) | Semi-auto (AR15) |
| Operation | Manual; nothing cycles | Gas operated | Gas operated |
| Subsonic ammunition | Any safe subsonic load runs | Load and gas setup matched | Load and gas setup matched |
| Suppressor | Enclosed | Enclosed for subsonic, flow-through for supersonic | Enclosed for subsonic, flow-through for supersonic |
| Trigger | TriggerTech Remington 700 Primary | TriggerTech Duty | TriggerTech Duty |
| Magazine | AICS pattern | AR10 pattern; AICS on the CM10 Centerfeed | AR15 pattern |
| More | CM7S bolt action rifles | CM10 AR10 rifles | Shop CM15 |
Choose CM15 AR15 rifles for the lightest semi-automatic package and cartridges that fit the AR15 magazine. Choose the CM10 for cartridges too long or too powerful for an AR15, and the CM7S for quiet subsonic shooting from the shortest package, since a bolt action adds no action noise. Read 300 Blackout bolt action vs semi-auto, 338 ARC bolt action vs semi-auto, 6.5 Grendel bolt action vs semi-auto and 6mm ARC bolt action vs semi-auto.
CM15 Uppers and Magazines
A complete CM15 upper turns an existing AR15 lower into a new cartridge. Each upper comes with the barrel, gas system and handguard installed, in your choice of receiver and handguard color, with the CM15 Low Mass bolt carrier group and ambidextrous charging handle as an option.
- 300 Blackout uppers: 5-inch, 7.5-inch, 10.5-inch and 16-inch
- 338 ARC uppers: 8.5-inch, 10.5-inch and 16-inch
- 5.56 NATO uppers: 8-inch, 10.5-inch and 16-inch
- 16-inch ARC and Grendel uppers: 6mm ARC, 22 ARC and 6.5 Grendel
- 400 Legend uppers: 10.5-inch and 16-inch
- Big-bore uppers: 458 SOCOM in 10.5 and 16 inches (1:14), 450 Bushmaster in 10.5 and 16 inches (1:24), and 12.7x42mm in 10.5 and 16 inches (1:20). The CM15 458 SOCOM uppers run standard 458 SOCOM; the longer 458 SOCOM XL needs the CM7S or CM10.
- Browse every one in CM15 uppers
- 30-round magazines: the 5.56 magazine and the 300 Blackout magazine, both ETS
- 10-round magazines: 338 ARC, 6mm ARC, 22 ARC, 6.5 Grendel, 350 Legend and 400 Legend
- Standard 5.56 magazines do not feed the wider ARC and Grendel cases, so use the magazine made for the cartridge. Browse every one in CM15 magazines and accessories
Suppressors for CM15 AR15 Rifles
With subsonic 300 Blackout or 338 ARC, Chattahoochee Munitions recommends an enclosed suppressor on the CM15, and the adjustable gas block and buffer tune the firearm to it. The CM15-SD is designed around an enclosed suppressor. With supersonic ammunition, including every 5.56 NATO, 6mm ARC, 22 ARC, 6.5 Grendel, 350 Legend and 400 Legend load, a flow-through suppressor is recommended on the CM15. Confirm the suppressor is rated for your caliber. Read the suppressor guides for 300 Blackout, 338 ARC, 5.56 NATO, 6mm ARC, 22 ARC and 6.5 Grendel.
CM15 AR15 Rifles FAQ
Who makes the CM15 AR15?
Chattahoochee Munitions manufactures the CM15 in Roswell, Georgia, as complete factory AR15 rifles, pistols and SBRs in eight cartridges, plus complete CM15 uppers and magazines.
Who makes a subsonic AR15?
Chattahoochee Munitions manufactures CM15 AR15 pistols and SBRs for subsonic 300 Blackout and 338 ARC with 1:5 twist barrels from 5 to 10.5 inches, and the CM15-SD 300 Blackout, which surrounds part of an enclosed suppressor with its handguard.
Which CM15 cartridges are subsonic?
300 Blackout and 338 ARC in the short 1:5 twist barrels. The 16-inch 1:7 300 Blackout is set up for owners who also shoot supersonic. 5.56 NATO, 6mm ARC, 22 ARC, 6.5 Grendel, 350 Legend and 400 Legend are supersonic.
What is the difference between a CM15 pistol and SBR?
The barrel, receivers and trigger are identical. The pistol uses a telescoping brace and the SBR uses a B5 Systems Bravo stock. The SBR is regulated under the National Firearms Act.
Can I put a CM15 upper on my AR15 lower?
CM15 uppers are manufactured around standard AR15 components and fit a standard AR15 lower. Use the magazine made for the cartridge, because 5.56 magazines do not feed the ARC or Grendel cases. Fit with other makers’ components is not guaranteed.
What suppressor should I use on a CM15?
An enclosed suppressor rated for the caliber with subsonic 300 Blackout or 338 ARC, and a flow-through suppressor with supersonic ammunition.
Which CM15 is for deer?
300 Blackout, 338 ARC, 6.5 Grendel, 6mm ARC, 350 Legend and 400 Legend with expanding hunting bullets. Chattahoochee Munitions does not recommend 5.56 NATO for deer.
How much does a CM15 weigh?
From 5 lb 10 oz for a 5-inch 300 Blackout pistol or SBR to 7 lb 4 oz for a 20-inch 22 ARC or 6.5 Grendel rifle, with an unloaded magazine. Listing weights are shipping weights.
What is the difference between the CM15 and the CM10?
Both are gas-operated semi-automatics with TriggerTech Duty triggers and adjustable gas. The CM15 is the AR15-size platform for cartridges that fit the AR15 magazine. The CM10 is the large-frame AR10 for longer cartridges such as 308 Winchester, 375 Raptor and 458 SOCOM XL.
Does Cobalt Kinetics Green Cerakote mean another company makes the CM15?
No. Cobalt Kinetics Green Cerakote is the finish color. Chattahoochee Munitions manufactures every CM15.