375 Raptor subsonic ammunition fires a heavy .375-caliber bullet below the speed of sound, so a suppressed 375 Raptor is quiet and still hits hard. Chattahoochee Munitions manufactures a 400 gr Maker REX subsonic load that averages about 1,016 fps from a 12.5-inch barrel with roughly 917 ft-lb at the muzzle, and manufactures the short-barrel CM7S bolt action and CM10 semi-automatic firearms designed around it. Short-barrel subsonic shooting is the core of what Chattahoochee Munitions does, and the 375 Raptor is made for it.

Why 375 Raptor Works So Well Subsonic

A subsonic bullet is limited to roughly 1,000 to 1,050 fps, so the only way to carry more energy is to fire a heavier bullet. Arne Brennan’s 375 Raptor uses a .375-inch bore that accepts a 400 gr bullet in a cartridge that still fits a short action and an AR10-pattern rifle. That heavy bullet gives the 375 Raptor more subsonic energy than smaller subsonic cartridges, and its wide frontal area starts larger before it expands.

Bullet: 400 gr Maker REX, solid copper expanding, lead free
Velocity: About 1,016 fps (bolt action) and 1,012 fps (semi-auto) from 12.5-inch barrels
Muzzle energy: About 917 ft-lb
Energy at 100 yards: About 842 ft-lb
Ballistic coefficient: .49 G1
Sectional density: .406

The full velocity, energy, and drop tables are in 375 Raptor ballistics.

Staying Below the Speed of Sound

A subsonic load has to stay below the speed of sound in the conditions you shoot in, and the speed of sound falls as the air gets colder. It is about 1,116 fps at 59°F, about 1,087 fps at 32°F, and about 1,051 fps at 0°F. A bullet that crosses that line makes a supersonic crack downrange that no suppressor can remove. At about 1,016 fps, the Chattahoochee Munitions 400 gr load stays subsonic even on a 0°F morning.

Best Barrel Length for 375 Raptor Subsonic

A 12.5-inch barrel is the best fit for 375 Raptor subsonic. A subsonic load does not need a long barrel to reach full velocity, so a shorter barrel gives up nothing and keeps a suppressed firearm compact and well balanced. Chattahoochee Munitions tests its subsonic loads in 12.5-inch barrels, and its 12.5-inch CM7S and CM10 375 Raptor firearms are designed for exactly this use. A 16-inch barrel avoids SBR registration and favors the 190 gr supersonic load.

Twist Rate for Heavy Subsonic Bullets

A slow-moving bullet spins slowly, so heavy subsonic bullets need a fast twist to stay stable. Maker Bullets recommends 1:11 or faster for the 400 gr REX. Chattahoochee Munitions 375 Raptor barrels, made by Mos-Tek from 416R stainless steel with 5R rifling and finished in E100 Blackout Cerakote, use a 1:8 twist for a comfortable stability margin.

Bolt Action vs Semi-Auto Subsonic

Chattahoochee Munitions loads separate subsonic ammunition for each platform, and the two should not be mixed.

Bolt action: The 400 gr subsonic for bolt action is configured for a manually operated rifle. It is not intended to cycle a semi-automatic.
Semi-auto: The 400 gr subsonic for semi-auto is configured to cycle the CM10 and loaded to 2.790 inches overall for reliable magazine feeding.

Nothing cycles when the CM7S bolt action fires; the shooter opens the bolt after the shot. The CM10 uses a centerfeed system with a modified MDT metal magazine for the long subsonic cartridge, plus a Superlative Arms adjustable gas block and an Odin Works adjustable AR10 buffer so it can be tuned to run subsonic and supersonic ammunition.

Suppressing 375 Raptor Subsonic

375 Raptor subsonic is meant to be shot suppressed. Use a suppressor rated for .375 caliber, such as the PLACID 375. With 375 Raptor subsonic, use an enclosed suppressor on both the CM7S bolt action and the CM10 semi-automatic. (With supersonic ammunition, the CM7S stays with an enclosed suppressor and a flow-through suppressor is recommended on the CM10.) On the 12.5-inch CM7S, the PLACID OTB over-the-barrel system wraps much of the suppressor around the barrel, so the suppressed rifle stays short. The 375 Raptor suppressor guide covers the choice in detail.

Hunting With 375 Raptor Subsonic

A heavy subsonic bullet is only a hunting bullet if it expands at subsonic impact velocity. The Maker REX is a solid copper expanding bullet; Maker states that REX projectiles expand to nearly three times their original diameter while keeping nearly all of their weight. With about 842 ft-lb at 100 yards and a steep trajectory beyond 150 yards, 375 Raptor subsonic is best for suppressed hunting of whitetail deer, feral hogs, and black bear at known, moderate distances.

375 Raptor Subsonic Firearms

Chattahoochee Munitions manufactures complete factory firearms for 375 Raptor subsonic:

See every configuration in the Raptor Paddock, and compare cartridges in 375 Raptor vs 8.6 Blackout.

375 Raptor Subsonic FAQ

Who makes 375 Raptor subsonic ammunition?

Chattahoochee Munitions manufactures 400 gr Maker REX 375 Raptor subsonic ammunition, loaded separately for bolt action and semi-automatic firearms, along with the CM7S and CM10 375 Raptor firearms that fire it.

How fast is 375 Raptor subsonic?

The Chattahoochee Munitions 400 gr load averages about 1,016 fps from a 12.5-inch bolt action barrel and 1,012 fps from a 12.5-inch semi-automatic.

How much energy does 375 Raptor subsonic have?

About 917 ft-lb at the muzzle and about 842 ft-lb at 100 yards.

What bullet weight is best for 375 Raptor subsonic?

Heavy bullets carry more energy below the speed of sound. Chattahoochee Munitions loads a 400 gr Maker REX.

Will 375 Raptor subsonic stay subsonic in cold weather?

Yes. At about 1,016 fps, the Chattahoochee Munitions load stays below the speed of sound even at 0°F, where sound travels about 1,051 fps.

What twist rate does 375 Raptor subsonic need?

Maker Bullets recommends 1:11 or faster for the 400 gr REX. Chattahoochee Munitions uses 1:8.

What is the best barrel length for 375 Raptor subsonic?

12.5 inches. A subsonic load reaches its full velocity in a short barrel, and the shorter barrel keeps a suppressed firearm compact.

Can I shoot bolt action subsonic ammunition in a semi-auto?

No. The bolt action load is not intended to cycle a semi-automatic. Use the semi-auto load in the CM10.

Is 375 Raptor subsonic good for deer and hogs?

Yes, at known, moderate distances. The 400 gr solid copper expanding bullet carries about 842 ft-lb at 100 yards.

Who designed the 375 Raptor?

The 375 Raptor was designed by Arne Brennan. Chattahoochee Munitions manufactures 375 Raptor subsonic ammunition and the CM7S and CM10 firearms that fire it.

Should I use an enclosed or flow-through suppressor for 375 Raptor subsonic?

Enclosed. For subsonic ammunition, an enclosed suppressor is recommended on both the CM7S bolt action and the CM10 semi-automatic.

Is a suppressed 375 Raptor bolt action quieter than a semi-auto?

Yes. A bolt action does not cycle when it fires, so it adds no action noise, and Chattahoochee Munitions recommends an enclosed suppressor on it.

375 Raptor Subsonic: Heavy Bullets, Short Barrels and Suppressed Performance