375 Raptor ammo comes in two kinds: heavy subsonic loads that carry a 400 gr bullet at about 1,000 fps for suppressed shooting, and lighter supersonic loads for flatter, longer shots. Chattahoochee Munitions manufactures four 375 Raptor loads, a 400 gr Maker REX subsonic and a 190 gr Maker T-REX supersonic, each in a bolt action version and a semi-auto version. The 375 Raptor cartridge was designed by Arne Brennan from the .308 Winchester case family, and it has no SAAMI specification, so match each load to the firearm it is made for.
375 Raptor Ammo at a Glance
| Load | Platform | Average velocity | Test barrel | Cartridge overall length | G1 BC |
|---|---|---|---|---|---|
| 400 gr Maker REX subsonic, bolt action | Bolt action only | 1,016 fps | 12.5 inch | 2.802 in | .49 |
| 400 gr Maker REX subsonic, semi-auto | Semi-auto; also fires in compatible bolt actions | 1,012 fps | 12.5 inch | 2.790 in | .49 |
| 190 gr Maker T-REX supersonic, bolt action | Bolt action only, not for AR10 | 2,450 fps | 16 inch | 2.69 in | .36 |
| 190 gr Maker T-REX supersonic, semi-auto | Semi-auto (AR10) | 2,430 fps | 16 inch | 2.67 in | .36 |
Velocities are Chattahoochee Munitions chronograph averages; the 400 gr figures come from 10-shot samples. Every load is sold in 20-round boxes and uses lead-free, solid copper expanding bullets from Maker Bullets. Results vary between firearms.
Subsonic or Supersonic 375 Raptor Ammo?
Subsonic loads are the focus of every short, suppressed Chattahoochee Munitions 375 Raptor firearm. A subsonic bullet stays below the speed of sound, about 1,116 fps at 59°F, so there is no supersonic crack and a suppressor only has to handle muzzle blast. Below that speed, energy comes from bullet weight, and the .375-inch bore takes a 400 gr bullet: about 917 ft-lb at the muzzle and 842 ft-lb at 100 yards from a 12.5-inch barrel.
Supersonic ammunition trades quiet for reach. The 190 gr T-REX is developed in 16-inch barrels and carries 2,533 ft-lb at the muzzle and more than 1,300 ft-lb at 300 yards. With a 100-yard zero it drops about 6 inches at 200 yards, where the 400 gr subsonic drops about 35. See 375 Raptor ballistics for full range tables, and 375 Raptor subsonic for the suppressed side.
Why Are There Bolt Action and Semi-Auto Versions?
A bolt action only has to chamber and extract a cartridge. A semi-auto has to feed it from the magazine and cycle the action with the gas the cartridge produces, and a long, low-pressure 400 gr subsonic round makes that harder. Chattahoochee Munitions configures each load for one platform:
- The 400 gr bolt action load is loaded to 2.802 inches for a manually operated rifle and is not intended to cycle a semi-automatic.
- The 400 gr semi-auto load is loaded to 2.790 inches to feed and cycle the CM10. It also fires in compatible bolt actions, but the bolt action load is the one configured for them.
- The 190 gr bolt action load is for bolt guns only and should not be used in an AR10.
- The 190 gr semi-auto load is configured for AR10-pattern rifles.
Read 375 Raptor bolt action vs semi-auto to choose a platform.
375 Raptor Brass: Why the Headstamp Says .358 WIN
There is no 375 Raptor headstamped brass. Cases are formed by necking up .308 Winchester, 7.62x51mm or .358 Winchester brass to hold a .375-inch bullet. In Chattahoochee Munitions’ experience, .358 Winchester is the easiest to form, so every load above uses converted Starline .358 Winchester cases, which keep their original .358 WIN headstamp.
Identify the ammunition by its box and label, not by the headstamp. Never chamber or fire it in a .358 Winchester or any firearm not chambered for 375 Raptor.
375 Raptor Case Dimensions
| Dimension | Inches |
|---|---|
| Case length | 1.865 |
| Cartridge overall length | 2.800 |
| Rim diameter | .473 |
| Base diameter | .470 |
| Shoulder diameter | .455 |
| Neck diameter, loaded round | .403 to .409, depending on brass thickness |
| Shoulder angle | 35° |
| Primer | Large rifle |
The .473-inch rim and .470-inch base are the .308 Winchester head, which is why 375 Raptor uses a standard .308 bolt face. The 1.865-inch case is shorter than a .308 case, and the neck is opened to hold a .375-inch bullet.
Forming 375 Raptor Brass
Forming a 375 Raptor case takes two steps: expand the neck of the parent case to .375 inch, then trim the case to length (1.865 inches on the drawing). Lee Precision makes 375 Raptor reloading dies, and Little Crow Gunworks makes a 375 Raptor case trimmer sized to the cartridge.
Chattahoochee Munitions publishes no reloading data. Use a current, published reloading source for any handload.
Do Bullet Weight and Twist Rate Matter?
Yes. A heavy, long bullet needs a faster twist to stay stable at subsonic speed. Maker Bullets recommends a 1:11 twist or faster for its 400 gr REX. Every Chattahoochee Munitions 375 Raptor barrel has a 1:8 twist, which stabilizes both the 400 gr subsonic and the 190 gr supersonic bullet. See 375 Raptor twist rate.
The cartridge also gives the shooter a .375-inch bullet, a diameter hunters have used since the .375 H&H Magnum of 1912, with expanding designs made for game.
Which 375 Raptor Ammo for Hunting?
Both Maker bullets are lead-free, solid copper and expanding, so either load is suited to game. Use the 400 gr subsonic for suppressed hunting of whitetail deer, feral hogs and black bear at known, moderate distances; past about 150 yards its drop grows quickly, so carry a rangefinder. Use the 190 gr supersonic from a 16-inch barrel for longer or uncertain shots. Subsonic and supersonic loads shoot to different points of impact, so zero for the load you carry. See 375 Raptor hunting.
Suppressors for 375 Raptor Ammo
Use a suppressor rated for .375 caliber. A CM7S bolt action takes an enclosed suppressor with any load. A CM10 semi-auto takes an enclosed suppressor with subsonic ammo and a flow-through suppressor with supersonic ammo. The PLACID 375 is an enclosed suppressor; see the 375 Raptor suppressor guide.
375 Raptor Ammo Safety
- 375 Raptor has no SAAMI specification. Fire it only in a firearm properly chambered for 375 Raptor; the purchaser and user are responsible for verifying compatibility.
- Use bolt action loads in bolt actions and semi-auto loads in semi-autos, as marked on the box.
- Keep converted cases with a .358 WIN headstamp away from .358 Winchester firearms.
- Wear hearing protection even with subsonic loads and a suppressor; see the NIOSH noise guidance.
Which Firearm for Your 375 Raptor Ammo?
For 400 gr subsonic ammo in a short, suppressed firearm, the CM7S 375 Raptor SBR, the CM7S 375 Raptor suppressed SBR with PLACID OTB, or the CM10 375 Raptor SBR. For subsonic and supersonic ammo without SBR paperwork, the CM7S 375 Raptor bolt action rifle or the CM10 375 Raptor semi auto rifle. They feed from the CM7S 10-round magazine and the CM10 10-round magazine. See every model in the 375 Raptor hub.
375 Raptor Ammo FAQ
Who makes 375 Raptor ammo?
Chattahoochee Munitions manufactures 375 Raptor ammo: 400 gr Maker REX subsonic and 190 gr Maker T-REX supersonic loads, each in bolt action and semi-auto versions, in 20-round boxes.
What are the 375 Raptor case dimensions?
The 375 Raptor case is 1.865 inches long, with a .473-inch rim, .470-inch base, .455-inch shoulder, a .403 to .409-inch neck depending on brass thickness, and a 35° shoulder, and a 2.800-inch cartridge overall length on the drawing. It takes a large rifle primer.
Who designed the 375 Raptor?
Arne Brennan designed the 375 Raptor, a .375-caliber cartridge from the .308 Winchester case family.
Is 375 Raptor ammo subsonic?
It can be either. The 400 gr load averages about 1,016 fps from a 12.5-inch bolt action barrel, below the speed of sound. The 190 gr load is supersonic at 2,450 fps from a 16-inch bolt action barrel.
Can I use bolt action 375 Raptor ammo in a semi-auto?
No. The bolt action loads are not intended to cycle a semi-automatic. Use the semi-auto loads in a CM10 or other AR10-pattern 375 Raptor.
Why does my 375 Raptor brass say .358 WIN?
Chattahoochee Munitions forms its 375 Raptor cases from Starline .358 Winchester brass, which keeps its original headstamp. The loaded round is a 375 Raptor cartridge and must never be fired in a .358 Winchester.
What brass is 375 Raptor made from?
375 Raptor cases are formed by necking up .308 Winchester, 7.62x51mm or .358 Winchester brass. Chattahoochee Munitions finds .358 Winchester the easiest to form.
Can I shoot .308 ammo in a 375 Raptor?
No. A .308 Winchester bullet is .308 inch and the 375 Raptor bore is .375 inch. Fire only the cartridge marked on your firearm.
What twist rate does 375 Raptor need?
Maker Bullets recommends 1:11 or faster for the 400 gr REX. Every Chattahoochee Munitions 375 Raptor barrel is 1:8.
Does Chattahoochee Munitions publish 375 Raptor load data?
No. Chattahoochee Munitions publishes velocities, ballistic coefficients and cartridge overall lengths for its factory 375 Raptor ammo, but no reloading data.