375 Raptor vs 338 ARC comes down to platform size and bullet weight. The 338 ARC, introduced by Hornady, puts a .338-caliber subsonic bullet (the 307 gr Sub-X) into an AR15-size rifle. The 375 Raptor, designed by Arne Brennan, puts a 400 gr .375-caliber subsonic bullet into a short bolt action or a large-frame AR10. Both are short-barrel subsonic cartridges at heart, and Chattahoochee Munitions manufactures complete CM7S bolt action firearms in both, plus CM15 AR15s in 338 ARC and CM10 AR10s in 375 Raptor.
375 Raptor vs 338 ARC at a Glance
| Feature | 375 Raptor | 338 ARC |
|---|---|---|
| Bullet diameter | .375 inch | .338 inch |
| Origin | Designed by Arne Brennan; .308 Winchester case family | Introduced by Hornady; ARC family |
| SAAMI status | No SAAMI specification published | SAAMI standardized (2.260 in maximum overall length, 52,000 psi) |
| Heavy subsonic bullet | 400 gr Maker REX (Chattahoochee Munitions load) | 307 gr Hornady Sub-X |
| Supersonic bullet | 190 gr Maker T-REX, 2,450 fps, 2,533 ft-lb (16-inch bolt action) | 175 gr |
| Semi-automatic platform | CM10 large-frame AR10 with centerfeed system | CM15 AR15 |
| Bolt action platform | CM7S, .308 bolt face | CM7S, 6.5 Grendel Type II bolt face |
| Chattahoochee Munitions barrel lengths | 12.5 and 16 inch | CM15: 8.5, 10.5, 16 inch; CM7S: 8, 12.5, 16 inch |
| Chattahoochee Munitions twist | 1:8 | 1:5 (CM7S and short CM15), 1:8 (16-inch CM15) |
| Magazine | CM10: modified MDT metal, 10 rounds; CM7S: AICS pattern | CM15: 10-round magazine, load 8; CM7S: MDT polymer AICS pattern, 10 rounds |
| Chattahoochee Munitions ammunition | Yes: subsonic and supersonic, bolt action and semi-auto loads | Not currently offered |
375 Raptor vs 338 ARC: Which Hits Harder Subsonic?
The 375 Raptor. Below the speed of sound both cartridges run at roughly the same velocity, so bullet weight decides the energy. Chattahoochee Munitions’ 400 gr Maker REX averages about 1,016 fps from a 12.5-inch barrel, roughly 917 ft-lb at the muzzle. At the same velocity, a 400 gr bullet carries about 30 percent more energy than a 307 gr bullet, and the .375-inch bullet starts wider before it expands. Hornady rates 338 ARC subsonic at about 1.5 times the energy of 300 Blackout subsonic, so the 338 ARC is a large step up within the AR15 envelope; the 375 Raptor is the next step beyond it.
See 375 Raptor subsonic and the 338 ARC subsonic guide for each cartridge in depth.
375 Raptor vs 338 ARC: AR15 or AR10?
This is the biggest practical difference. The 338 ARC fits the AR15 cartridge envelope, so the CM15 delivers heavy .338-caliber subsonic performance in a lighter, more compact AR15 with adjustable gas and an adjustable buffer. The 375 Raptor is a .308-family cartridge, so its semi-automatic is the large-frame CM10, which uses a centerfeed system and a modified MDT metal magazine to feed the long 400 gr subsonic cartridge (2.790 inches overall). The CM10 375 Raptor weighs about 7.5 lb as a 12.5-inch SBR and 7.75 lb as a 16-inch rifle.
- Choose 338 ARC when you want heavy subsonic performance in a smaller, lighter AR15 platform.
- Choose 375 Raptor when you want the heaviest subsonic bullet and are comfortable with an AR10-size semi-auto or a short bolt action.
375 Raptor vs 338 ARC in a Short Barrel
Both cartridges are made for short barrels. Chattahoochee Munitions’ testing found 338 ARC powder use levels off around 12 inches, and the 400 gr 375 Raptor subsonic load is tested from 12.5-inch barrels. The 338 ARC goes shorter in the Chattahoochee Munitions lineup: 8.5 and 10.5-inch CM15s and an 8-inch CM7S. The 375 Raptor’s shortest configuration is 12.5 inches in both the CM7S and the CM10, including the CM7S with the PLACID OTB over-the-barrel suppressor.
375 Raptor vs 338 ARC Twist Rate
Heavy subsonic bullets need a fast twist. Chattahoochee Munitions uses a 1:5 twist for 338 ARC in the CM7S and the short CM15s, and 1:8 on the 16-inch CM15. Every Chattahoochee Munitions 375 Raptor barrel, made by Mos-Tek from 416R stainless steel with 5R rifling and finished in E100 Blackout Cerakote, uses a 1:8 twist, faster than Maker Bullets’ guidance of 1:11 or faster for the 400 gr REX.
375 Raptor vs 338 ARC Supersonic Performance
For supersonic shooting, the 375 Raptor fires a 190 gr Maker T-REX at 2,450 fps from a 16-inch bolt action barrel, 2,533 ft-lb at the muzzle and more than 1,300 ft-lb at 300 yards. The 338 ARC also has a 175 gr supersonic load. If supersonic hunting matters as much as subsonic, the larger 375 Raptor case gives more room to work. Full tables are in 375 Raptor ballistics.
375 Raptor vs 338 ARC Suppressors
Both cartridges are made to be shot suppressed. A suppressor rated for .375 caliber, such as the PLACID 375, rated from 5.56 NATO through .375, covers both. For subsonic ammunition, an enclosed suppressor is recommended on both bolt action and semi-automatic firearms. For supersonic ammunition, the bolt action stays with an enclosed suppressor, while a flow-through suppressor is recommended on the semi-automatic. A suppressed firearm is still not hearing safe, so use hearing protection.
375 Raptor vs 338 ARC Ammunition
The 338 ARC is SAAMI standardized and Hornady loads factory 338 ARC ammunition, including the 307 gr Sub-X subsonic. The 375 Raptor has no SAAMI specification, and Chattahoochee Munitions manufactures its own 375 Raptor ammunition with Maker Bullets projectiles: 400 gr subsonic for bolt action, 400 gr subsonic for semi-auto, and 190 gr supersonic loads for each platform.
375 Raptor vs 338 ARC: Which Should You Choose?
- Choose 375 Raptor for the heaviest subsonic bullet, a stronger supersonic load, and firearms and ammunition from the same manufacturer.
- Choose 338 ARC for an AR15-size semi-auto, the shortest barrels, and SAAMI-standardized factory ammunition.
Explore 375 Raptor firearms in the Raptor Paddock, including the 12.5-inch CM7S 375 Raptor and the 12.5-inch CM10 375 Raptor SBR. Explore 338 ARC in Containment Zone 338, including the 10.5-inch CM15 338 ARC and the 12.5-inch CM7S 338 ARC. For another heavy subsonic comparison, read 375 Raptor vs 8.6 Blackout.
375 Raptor vs 338 ARC FAQ
Who makes 375 Raptor and 338 ARC rifles?
Chattahoochee Munitions manufactures complete factory firearms in both cartridges: CM7S bolt action rifles, SBRs, and pistols in both; CM10 AR10 rifles and SBRs in 375 Raptor; and CM15 AR15 rifles, pistols, and SBRs in 338 ARC.
Which is better, 338 ARC or 375 Raptor?
It depends on the platform. The 338 ARC is better for an AR15-size semi-auto and the shortest barrels. The 375 Raptor is better for the heaviest subsonic bullet and a stronger supersonic load.
Is 375 Raptor more powerful than 338 ARC?
Yes. In 375 Raptor vs 338 ARC energy terms, At subsonic speed the 400 gr 375 Raptor bullet carries about 30 percent more energy than a 307 gr 338 ARC bullet, and its 190 gr supersonic load reaches 2,533 ft-lb at the muzzle.
Can 375 Raptor run in an AR15?
No. The 375 Raptor is a .308-family cartridge and needs a large-frame AR10 such as the CM10, or a short bolt action such as the CM7S. The 338 ARC is the AR15 option.
Who designed the 375 Raptor and the 338 ARC?
The 375 Raptor was designed by Arne Brennan. The 338 ARC was introduced by Hornady.
What twist rate do 375 Raptor and 338 ARC use?
Chattahoochee Munitions uses 1:8 for 375 Raptor, and 1:5 for 338 ARC except the 16-inch CM15, which uses 1:8.
What is the best barrel length for subsonic 375 Raptor or 338 ARC?
About 12 to 12.5 inches for both. Shorter 338 ARC barrels trade some velocity for a more compact suppressed firearm.
Can one suppressor work on 375 Raptor and 338 ARC?
Yes, if it is rated for .375 caliber. The PLACID 375 is rated from 5.56 NATO through .375.
Is 338 ARC SAAMI standardized? Is 375 Raptor?
The 338 ARC is SAAMI standardized. No SAAMI specification has been published for 375 Raptor.