338 ARC bolt action vs semi auto comes down to what you want from a suppressed subsonic firearm. A bolt action is manually operated, so it adds no action noise and never needs subsonic ammunition to cycle it. A semi-automatic AR15 gives fast follow-up shots and tunes to subsonic, supersonic and suppressed use with an adjustable gas system. Chattahoochee Munitions manufactures both: the CM7S bolt action in 8, 12.5 and 16-inch barrels and the CM15 AR15 in 8.5, 10.5 and 16-inch barrels, both with the 6.5 Grendel Type II bolt face.
338 ARC Bolt Action vs Semi Auto at a Glance
| Feature | CM7S bolt action | CM15 semi-automatic |
|---|---|---|
| Operation | Manual, three-lug bolt, 60-degree throw | Gas operated AR15 |
| Action / receivers | CM7S action, Remington 700 footprint, full PVD coating | CM15 7075-T6 billet upper and lower |
| Bolt face | 6.5 Grendel Type II | 6.5 Grendel Type II, 9310 steel bolt, low mass bolt carrier group |
| Barrel lengths | 8, 12.5, 16 inch | 8.5, 10.5, 16 inch |
| Twist | 1:5 (8 inch), 1:6 (12.5 and 16 inch) | 1:5 (8.5 and 10.5 inch), 1:8 (16 inch) |
| Barrel | Mos-Tek 416R stainless, 5R, E100 Blackout Cerakote | 416R stainless, E100 Blackout Cerakote |
| Trigger | TriggerTech R700 Primary, 1.5 to 4.0 lb | TriggerTech AR15 Duty, 3.5 lb |
| Gas and buffer | None | Superlative Arms adjustable gas block, Odin Works adjustable buffer |
| Magazine | 10-round MDT polymer AICS pattern | 10-round 338 ARC AR15 magazine |
| Weight (12.5 / 10.5 inch) | 6 lb 6 oz | 6 lb 10 oz |
Suppressed Subsonic: Bolt Action
A bolt action has no gas system venting at the ejection port and no bolt carrier cycling, so with subsonic ammunition and an enclosed suppressor it adds no action noise to the shot. It also has no cycling requirement, so any subsonic load runs regardless of pressure. The CM7S suits hunters who want a low report and a precise trigger: a TriggerTech R700 Primary adjustable from 1.5 to 4.0 lb, a CM7 billet chassis and the CM Precision Vertical Crossover Grip.
Suppressed Subsonic: Semi-Automatic
A semi-automatic has to cycle on subsonic pressure and handle the extra back pressure a suppressor adds. The CM15 uses a Superlative Arms adjustable gas block and an Odin Works adjustable buffer, so the same firearm can be tuned for subsonic or supersonic ammunition, suppressed or not. It gives fast follow-up shots for hogs and a familiar AR15 manual of arms, with a Breek Arms collaboration ambidextrous charging handle and B5 Systems furniture.
Suppressor Choice by Platform
338 ARC bolt action vs semi auto also changes the suppressor recommendation:
- CM7S bolt action: An enclosed suppressor, with subsonic or supersonic ammunition.
- CM15 with subsonic ammunition: An enclosed suppressor.
- CM15 with supersonic ammunition: A flow-through suppressor.
See 338 ARC suppressor for the reasons.
Accuracy and Trigger
Both platforms use 416R stainless barrels finished in E100 Blackout Cerakote, and the CM7S barrels come from Mos-Tek with 5R rifling. The bolt action’s adjustable trigger and fixed action suit precise shooting from a rest. The CM15’s 3.5 lb TriggerTech Duty trigger, in single-stage straight, single-stage curved or two-stage straight, suits field shooting and fast follow-ups.
Size and Weight
In 338 ARC bolt action vs semi auto terms, the two platforms are close in weight at the same barrel length. The CM7S 12.5-inch weighs 6 lb 6 oz and the CM15 10.5-inch weighs 6 lb 10 oz. The CM7S goes down to an 8-inch barrel at 5 lb 12 oz and 20.5 inches overall with the stock collapsed; the CM15 goes down to 8.5 inches at 5 lb 14 oz.
Magazines
Magazines are the clearest 338 ARC bolt action vs semi auto difference: the two platforms use different ones. The CM7S uses a 10-round MDT polymer AICS-pattern 338 ARC bolt action magazine. The CM15 uses a 10-round 338 ARC AR15 magazine made for the wider ARC case; standard 5.56 magazines do not feed 338 ARC. Every firearm ships with one magazine.
338 ARC Bolt Action vs Semi Auto: Which Should You Choose?
- Choose the CM7S bolt action for no action noise, any subsonic load without tuning, and an adjustable precision trigger.
- Choose the CM15 semi-automatic for fast follow-up shots, AR15 controls, and one firearm tuned for subsonic and supersonic ammunition.
Shop the CM7S 338 ARC 12.5-inch bolt action, the CM7S 338 ARC 16-inch bolt action rifle, the CM15 338 ARC 10.5-inch AR15 and the CM15 338 ARC 16-inch AR15 rifle, or see every configuration in Containment Zone 338. Read 338 ARC subsonic and 338 ARC barrel length next.
338 ARC Bolt Action vs Semi Auto FAQ
Is a 338 ARC bolt action quieter than an AR15?
Suppressed with subsonic ammunition, a bolt action adds no action noise and no gas at the ejection port, so the report is lower. The difference shrinks with a well-tuned semi-automatic and an enclosed suppressor.
Do the CM7S and CM15 use the same 338 ARC ammunition?
Yes. Both are chambered in SAAMI 338 ARC and fire the same factory ammunition. The CM15’s adjustable gas lets it cycle subsonic and supersonic loads.
Do the bolt action and AR15 use the same magazine?
No. The CM7S uses a 10-round MDT polymer AICS-pattern magazine. The CM15 uses a 10-round 338 ARC AR15 magazine.
What bolt face does 338 ARC use?
The 6.5 Grendel Type II bolt face, on both the CM7S and the CM15.
Will a 338 ARC AR15 cycle subsonic ammunition?
The CM15 is made to. Its adjustable gas block and adjustable buffer let you tune it for subsonic ammunition, with or without a suppressor.
Which has more recoil?
At the same load, a semi-automatic spreads recoil over the bolt carrier’s travel, while a bolt action delivers it at once. With subsonic ammunition, both are mild.
Can the CM7S use Remington 700 parts?
The CM7S action uses the Remington 700 footprint, so many Remington 700 pattern triggers, chassis and stocks fit. Chattahoochee Munitions also offers 338 ARC barreled actions.
Who makes a 338 ARC bolt action and a 338 ARC AR15?
Chattahoochee Munitions manufactures both: the CM7S bolt action in 8, 12.5 and 16 inches, and the CM15 AR15 in 8.5, 10.5 and 16 inches, as pistols, SBRs and rifles.