Containment Zone 338: 338 ARC Rifles, Pistols and SBRs
Chattahoochee Munitions manufactures complete 338 ARC firearms on two platforms: the CM7S bolt action as 8, 10 and 12.5-inch pistols or SBRs and 16-inch rifles, including walnut-stocked models with WOOX furniture; and the CM15 AR15 as 8.5-inch and 10.5-inch pistols or SBRs and 16-inch rifles. It also manufactures 338 ARC uppers, CM7S barreled actions and magazines for both platforms. Start with 338 ARC subsonic or 338 ARC vs 300 Blackout.
338 ARC is a .338-caliber AR15 cartridge made for short-barrel subsonic shooting. Its 307 gr subsonic bullet carries about 752 ft-lb at 1,050 fps, stays below the speed of sound for a suppressed shot without the sonic crack, and still fits the AR15’s 2.260-inch magazine length.
What Is 338 ARC?
338 ARC (Advanced Rifle Cartridge) is a .338-caliber cartridge introduced by Hornady as part of its ARC family. It shares the .441-inch case head of the 6.5 Grendel, so it runs on the 6.5 Grendel Type II bolt face, and it is sized for the AR15 magazine. SAAMI published its 338 ARC specification in January 2025. The cartridge was designed around a heavy subsonic bullet, and supersonic loads give it a second role for flatter shooting.
338 ARC Specifications at a Glance
- Bullet diameter: .338 inch
- Case: 1.300 inches, .441-inch head (ARC and 6.5 Grendel family)
- Overall length: 2.260 inches maximum (AR15 magazine length)
- Pressure: 52,000 psi maximum average (SAAMI)
- Bolt face: 6.5 Grendel Type II
- Subsonic load: 307 gr Sub-X, 1,050 fps, 752 ft-lb (Hornady, 16-inch barrel)
- Supersonic loads: 170 to 215 gr; 175 gr HP Match at 2,075 fps, 1,673 ft-lb (Hornady, 16-inch barrel)
- Chattahoochee Munitions twist: 1:6 on the 8, 12.5 and 16-inch CM7S, 1:5 on the 10-inch CM7S and the 8.5 and 10.5-inch CM15, 1:8 on the 16-inch CM15
- Chattahoochee Munitions barrels: 416R stainless, E100 Blackout Cerakote, 5/8×24 threads
CM7S Bolt Action Rifles, Pistols, and SBRs
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CM7S 338 ARC
CM7S 338 ARC Subsonic Rifle 10″ Bolt Action SBR or Pistol – FDE Metallic Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC Subsonic Pistol 10″ Bolt Action or SBR – Cobalt Kinetics Green Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC Subsonic Bolt Action 10″ Pistol or SBR – Black Tungsten Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 16″ Bolt Action Rifle – Cobalt Kinetics Green Cerakote
$2,649.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 16″ Bolt Action Rifle – FDE Metallic Cerakote
$2,649.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 16″ Bolt Action Rifle – Black Tungsten Cerakote
$2,649.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 16″ Bolt Action Hunting Rifle – WOOX Walnut Stock
$2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 12.5″ Bolt Action SBR – WOOX Walnut Stock
$2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 8″ Bolt Action Pistol or SBR – Cobalt Kinetics Green Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 12.5″ Bolt Action Pistol or SBR – Cobalt Kinetics Green Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 8″ Bolt Action Pistol or SBR – FDE Metallic Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 12.5″ Bolt Action Pistol or SBR – FDE Metallic Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 12.5″ Bolt Action Pistol or SBR – Black Tungsten Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM7S 338 ARC
CM7S 338 ARC 8″ Compact Bolt Action Pistol or SBR – Black Tungsten Cerakote
Price range: $2,649.00 through $2,749.00 Select options This product has multiple variants. The options may be chosen on the product page
CM15 Semi-Automatic Rifles, Pistols, and SBRs
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CM 338 ARC
CM15 338 ARC 16″ AR15 Rifle – Cobalt Kinetics Green Cerakote
Price range: $1,695.91 through $1,785.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM 338 ARC
CM15 338 ARC 16″ AR15 Rifle – FDE Metallic Cerakote
Price range: $1,695.91 through $1,785.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM 338 ARC
CM15 338 ARC 16″ AR15 Rifle – Black Tungsten Cerakote
Price range: $1,695.91 through $1,785.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 8.5″ AR15 Pistol or SBR – Black Tungsten Cerakote
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 10.5″ AR15 Pistol or SBR – FDE Metallic Cerakote
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 8.5″ AR15 Pistol or SBR – FDE Metallic Cerakote
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 8.5″ AR15 Pistol or SBR – Cobalt Kinetics Green Cerakote and Coyote
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 10.5″ AR15 Pistol or SBR – Cobalt Kinetics Green Cerakote and Coyote
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 AR15 Firearms
CM15 338 ARC 10.5″ AR15 Pistol or SBR – Black Tungsten Cerakote and Black
Price range: $1,785.91 through $1,975.91 Select options This product has multiple variants. The options may be chosen on the product page
CM15 Premium Uppers
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CM15 Uppers
CM15 338 ARC 8.5″ 1:5 Twist Upper with Options
Price range: $789.00 through $989.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 Uppers
CM15 338 ARC 10.5″ 1:5 Twist Upper with Options
Price range: $789.00 through $989.00 Select options This product has multiple variants. The options may be chosen on the product page -
CM15 Uppers
CM15 338 ARC 16″ Upper with Options
Price range: $789.00 through $989.00 Select options This product has multiple variants. The options may be chosen on the product page
CM7S Barreled Actions
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Approximate Lead Time is 3-4 Weeks
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Approximate Lead Time is 3-4 Weeks
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Approximate Lead Time is 4-6 Weeks
Magazines
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CM7S Accessories
CM7S 338 ARC Bolt Action Magazine – 10 Round MDT AICS
Price range: $49.99 through $59.99 Select options This product has multiple variants. The options may be chosen on the product page -
Magazines
CM15 338 ARC AR15 Magazine – 10 Round
Price range: $27.90 through $37.90 Select options This product has multiple variants. The options may be chosen on the product page
338 ARC Subsonic: Heavy Bullets, Short Barrels, Suppressors
Short-barrel subsonic shooting is the core of Containment Zone 338. Below the speed of sound, energy comes from bullet weight, and Hornady rates 338 ARC subsonic at about 1.5 times the energy of 300 Blackout subsonic. A subsonic load is capped by the speed of sound, not by the barrel, and in Chattahoochee Munitions testing 338 ARC powder use is largely complete around 12 inches. That is why the 12.5-inch CM7S and the 10.5-inch CM15 sit at the center of the lineup, with 8 and 10-inch CM7S and 8.5-inch CM15 options for a smaller suppressed host.
With subsonic ammunition, use an enclosed suppressor on both the CM7S and the CM15. With supersonic ammunition, the bolt action stays with an enclosed suppressor and a flow-through suppressor is recommended on the CM15. The PLACID 375 is an enclosed suppressor rated from 5.56 NATO through .375.
CM7S 338 ARC Bolt Action
The CM7S is manually operated, so it adds no action noise when suppressed and runs any subsonic load without tuning. Chattahoochee Munitions manufactures it on a full PVD coated action with the Remington 700 footprint, a three-lug bolt with a 60-degree throw and the 6.5 Grendel Type II bolt face, a Mos-Tek 416R stainless barrel with 5R rifling, a TriggerTech R700 Primary trigger adjustable from 1.5 to 4.0 lb, the CM7 billet chassis and a 10-round MDT polymer AICS-pattern magazine.
- 8 inch, 1:6: pistol or SBR, 5 lb 12 oz, 20.5 to 28.0 inches overall
- 10 inch, 1:5: pistol or SBR, 5 lb 15 oz, 22.5 to 30.0 inches overall
- 12.5 inch, 1:6: pistol or SBR, 6 lb 6 oz, 26.0 to 32.5 inches overall
- 16 inch, 1:6: rifle, 7 lb 4 oz, 28.5 to 36.0 inches overall
- Walnut-stocked CM7S with WOOX furniture: 12.5-inch SBR and 16-inch rifle
CM15 338 ARC AR15
The CM15 is a gas-operated AR15 that Chattahoochee Munitions manufactures for both subsonic and supersonic 338 ARC. A Superlative Arms adjustable gas block and an Odin Works adjustable buffer let it be tuned for suppressed and unsuppressed use. It uses CNC-machined 7075-T6 billet receivers, a low mass bolt carrier group with a Type II spec 9310 steel bolt, a CM ambidextrous charging handle made in collaboration with Breek Arms, a 3.5 lb TriggerTech AR15 Duty trigger, B5 Systems furniture and a 10-round 338 ARC AR15 magazine.
- 8.5 inch, 1:5: pistol or SBR, 5 lb 14 oz
- 10.5 inch, 1:5: pistol or SBR, 6 lb 10 oz
- 16 inch, 1:8: rifle, 6 lb 10 oz
Complete CM15 338 ARC uppers come in the same three lengths, with an optional bolt carrier group and charging handle.
338 ARC Barreled Actions and Magazines
CM7S 338 ARC barreled actions come in 8, 12.5 and 16 inches with the Remage barrel nut system, for a stock or chassis of your choice. Each firearm ships with one magazine, and spare magazines are available for both platforms: the 338 ARC bolt action magazine for the CM7S and the 338 ARC AR15 magazine for the CM15.
Bolt Action or AR15?
- Choose the CM7S for no action noise, any subsonic load without tuning, an adjustable precision trigger and barrels down to 8 inches.
- Choose the CM15 for fast follow-up shots, AR15 controls, and one firearm tuned for subsonic and supersonic ammunition.
Read 338 ARC bolt action vs semi auto for the full comparison.
338 ARC Guides
- 338 ARC subsonic
- Ballistics
- Twist rate
- Barrel length
- Suppressor guide
- Hunting
- Bolt action vs semi auto
- vs 300 Blackout
- vs 8.6 Blackout
- vs 6.5 Grendel
- 375 Raptor vs 338 ARC
338 ARC FAQ
Who makes a 338 ARC rifle?
Chattahoochee Munitions manufactures complete 338 ARC firearms: the CM7S bolt action as 8, 10 and 12.5-inch pistols or SBRs and 16-inch rifles, including walnut-stocked models with WOOX furniture, and the CM15 AR15 as 8.5-inch and 10.5-inch pistols or SBRs and 16-inch rifles.
Who makes a 338 ARC bolt action rifle?
Chattahoochee Munitions manufactures the CM7S bolt action in 338 ARC with Mos-Tek barrels in 8, 10, 12.5 and 16 inches, plus barreled actions in 8, 12.5 and 16 inches.
Is 338 ARC an AR15 cartridge?
Yes. It fits the AR15’s 2.260-inch magazine length and runs with a 338 ARC barrel, a 6.5 Grendel Type II bolt and a 338 ARC magazine. It also runs in short bolt actions such as the CM7S.
What is 338 ARC used for?
Suppressed subsonic shooting, and hunting hogs, deer and medium game at moderate range. Supersonic loads add flatter shooting.
What twist rate does Chattahoochee Munitions use for 338 ARC?
1:6 on the 8, 12.5 and 16-inch CM7S, 1:5 on the 10-inch CM7S and the 8.5 and 10.5-inch CM15, and 1:8 on the 16-inch CM15.
What barrel length is right for 338 ARC?
For subsonic, about 10.5 to 12.5 inches; Chattahoochee Munitions testing shows powder use is largely complete around 12 inches. Choose 16 inches if supersonic loads matter as much.
What suppressor should I use on 338 ARC?
One rated for .338 caliber or larger: enclosed on a bolt action and on an AR15 with subsonic ammunition, flow-through on an AR15 with supersonic ammunition.
Does Chattahoochee Munitions sell 338 ARC ammunition?
No. Chattahoochee Munitions manufactures 338 ARC firearms, uppers, barreled actions and magazines. Factory ammunition is loaded by Hornady.