The best 375 Raptor twist rate for heavy subsonic bullets is 1:8, one full turn in eight inches. A 400 gr subsonic bullet moves slowly, so it spins slowly, and it needs a fast twist to stay stable all the way to the target. Maker Bullets recommends 1:11 or faster for its 400 gr REX, and Chattahoochee Munitions manufactures every 375 Raptor barrel it offers with a 1:8 twist for a wide stability margin. The barrel also has to handle the 190 gr supersonic load, and 1:8 stabilizes both. The cartridge was designed by Arne Brennan; this guide explains why Chattahoochee Munitions chose 1:8 for it.

375 Raptor Twist Rate at a Glance

Item	Figure
Chattahoochee Munitions 375 Raptor twist rate	1:8 on every barrel, 12.5 and 16 inch, bolt action and semi-auto
Twist in calibers	About 21 calibers (8 in / .375 in)
Maker Bullets guidance, 400 gr REX	1:11 or faster
Spin rate, 400 gr subsonic at 1,016 fps, 1:8	About 91,000 rpm
Spin rate, same load, 1:11	About 66,500 rpm
Spin rate, 190 gr supersonic at 2,450 fps, 1:8	About 220,000 rpm
Barrel	Mos-Tek, 416R stainless steel, 5R rifling, 11/16×24 threads, E100 Blackout Cerakote

Spin rate is muzzle velocity in inches per second divided by twist length, converted to revolutions per minute.

Why Subsonic Bullets Need a Faster 375 Raptor Twist Rate

Rifling spins a bullet so it flies point first instead of tumbling. How fast it spins depends on two things: the twist rate and how fast the bullet is moving. A supersonic bullet at 2,450 fps spins more than twice as fast as a subsonic bullet at 1,016 fps through the same barrel. That is why heavy subsonic cartridges, the core of short-barrel subsonic shooting, call for faster twist rates than their supersonic cousins.

Bullet length matters too. Stability depends on how long a bullet is, not only on its weight, and a solid copper bullet is longer than a lead-core bullet of the same weight because copper is less dense. The 400 gr Maker REX is a long, heavy, solid copper bullet, which is exactly the kind of bullet that needs a fast twist.

Why Chattahoochee Munitions Chose a 1:8 375 Raptor Twist Rate

Under the widely used Miller stability rule, a bullet’s gyroscopic stability rises with the square of the twist rate. Moving from 1:11 to 1:8 raises the stability factor by about 89 percent, since (11/8)² is about 1.89. That margin covers the conditions that reduce stability in the field: cold, dense air, temperature swings, and small lot-to-lot differences in velocity.

Once a bullet is fully stable, extra spin does not add accuracy, so there is no reason to go faster than needed. A 1:8 twist gives the 400 gr subsonic bullet a wide margin over Maker Bullets’ 1:11 guidance and still handles the shorter 190 gr supersonic bullet, which stabilizes easily at 2,450 fps. One twist rate for both loads means one barrel runs the full Chattahoochee Munitions ammunition lineup.

375 Raptor Twist Rate and Accuracy With a Suppressor

A suppressor makes stability even more important. A bullet that is only marginally stable can yaw as it leaves the muzzle, and in the worst case it can strike a baffle. A 1:8 twist keeps the 400 gr bullet flying point first through the suppressor and downrange. Use a suppressor rated for .375 caliber, such as the PLACID 375. For subsonic ammunition, an enclosed suppressor is recommended on both the CM7S bolt action and the CM10 semi-automatic. For supersonic ammunition, the CM7S stays with an enclosed suppressor, while a flow-through suppressor is recommended on the CM10.

Is There a Standard 375 Raptor Twist Rate?

No. No SAAMI specification has been published for the 375 Raptor, so there is no standardized 375 Raptor twist rate, and each barrel maker chooses its own. Chattahoochee Munitions barrels are made by Mos-Tek from 416R stainless steel with 5R rifling and a 1:8 twist, then finished in E100 Blackout Cerakote. If you load bullets other than the Chattahoochee Munitions loads, check the bullet maker’s twist recommendation against your barrel before you shoot.

375 Raptor Twist Rate by Firearm

Every 375 Raptor firearm Chattahoochee Munitions manufactures uses the same 1:8 twist:

Browse every configuration in the Raptor Paddock. For barrel length choices, read 375 Raptor barrel length, and for the heavy subsonic load itself, read 375 Raptor subsonic.

375 Raptor Twist Rate FAQ

What is the best twist rate for 375 Raptor?

1:8 for heavy subsonic bullets. Maker Bullets recommends 1:11 or faster for the 400 gr REX, and Chattahoochee Munitions uses 1:8 on every 375 Raptor barrel for a wide stability margin.

Who makes 375 Raptor barrels with a 1:8 twist?

Chattahoochee Munitions manufactures 375 Raptor firearms and barrels with a 1:8 twist, made by Mos-Tek from 416R stainless steel with 5R rifling and finished in E100 Blackout Cerakote.

Why do subsonic bullets need a faster twist rate?

A bullet’s spin depends on its velocity as well as the twist. A subsonic bullet moves slowly, so it spins slowly, and a heavy, long subsonic bullet needs a faster twist to stay stable.

Will a 1:8 twist shoot 375 Raptor supersonic ammunition?

Yes. The 190 gr supersonic bullet is shorter and faster, so it stabilizes easily in a 1:8 twist.

Is a 1:11 twist enough for 400 gr 375 Raptor subsonic?

Maker Bullets lists 1:11 as the minimum for the 400 gr REX. A 1:8 twist raises the stability factor by about 89 percent over 1:11.

How fast does a 375 Raptor subsonic bullet spin?

At 1,016 fps through a 1:8 twist, the 400 gr bullet spins at about 91,000 rpm as it leaves the muzzle.

Is there a SAAMI twist rate for 375 Raptor?

No. No SAAMI specification has been published for the 375 Raptor, so twist rate is chosen by each barrel maker.

Do the CM7S and CM10 use the same twist rate?

Yes. Every Chattahoochee Munitions 375 Raptor barrel, bolt action or semi-auto, 12.5 or 16 inch, uses a 1:8 twist.

Who designed the 375 Raptor?

The 375 Raptor was designed by Arne Brennan. Chattahoochee Munitions manufactures 375 Raptor firearms, barrels, and ammunition.

375 Raptor Twist Rate: Why 1:8 for Heavy Subsonic Bullets