Chattahoochee Munitions manufactures this 458 SOCOM semi auto ammo for its CM10: a 650 gr Maker REX solid copper expanding bullet in factory-new Starline 458 SOCOM brass, loaded as 458 SOCOM XL to 2.790 inches with a propellant configuration that cycles the CM10. From a 12.5-inch CM10 barrel it averages about 1,012 fps and about 1,478 ft-lb at the muzzle. Twenty rounds per box.
Standard 458 SOCOM is limited to 2.260 inches overall by the AR15 magazine. 458 SOCOM XL moves past that limit: the 2.035-inch, 650 gr subsonic projectile is seated less deeply, reclaiming usable case capacity for powder. See every configuration on Terminal 458.
Loaded for the CM10 Centerfeed Semi-Automatic
This 458 SOCOM semi auto ammo is loaded for the centerfeed CM10 large-frame semi-automatic. It is 2.790 inches overall, too long for an AR15, and it is not the same as the 2.802-inch 458 SOCOM subsonic ammo for bolt action. Use it with the 458 SOCOM XL magazine and a barrel with a 1:10 twist or faster. See the 458 SOCOM semi auto SBR and 458 SOCOM semi auto rifle.
Why 650 gr Subsonic in a Semi-Automatic
A heavy subsonic bullet carries its energy in weight rather than speed, and at about 1,012 fps it stays below the speed of sound even at 0°F. With subsonic ammunition, Chattahoochee Munitions recommends an enclosed suppressor on the CM10, and its adjustable gas block and buffer tune the rifle to cycle this load suppressed. Read 458 SOCOM subsonic and the 458 SOCOM suppressor guide.
Maker REX Projectile
The 650 gr REX is CNC-machined from solid copper and is lead free. It is 2.035 inches long, with a sectional density of .443 and a ballistic coefficient of .44 G1. Maker designs REX projectiles to expand at subsonic velocity. The trajectory is nearly identical to the bolt action load; full tables are in 458 SOCOM ballistics.
458 SOCOM Semi Auto Ammo Specifications
- Manufacturer: Chattahoochee Munitions
- Cartridge: 458 SOCOM, loaded as 458 SOCOM XL
- Bullet: 650 gr Maker REX, solid copper, expanding, lead free
- Bullet diameter: .458 inch
- Projectile length: 2.035 inches
- Sectional density: .443
- Ballistic coefficient: .44 G1
- Brass: Factory-new Starline 458 SOCOM
- Cartridge overall length: 2.790 inches
- Velocity: About 1,012 fps, 12.5-inch CM10 barrel
- Muzzle energy: About 1,478 ft-lb
- Twist required: 1:10 or faster
- Platform: CM10 centerfeed semi-automatic
- Magazine: 458 SOCOM XL magazine, modified MDT metal AICS pattern
- Quantity: 20 rounds
458 SOCOM Semi Auto Ammo FAQ
Who makes 650 gr 458 SOCOM semi auto ammo?
Chattahoochee Munitions manufactures 650 gr Maker REX 458 SOCOM semi auto ammo, loaded as 458 SOCOM XL to 2.790 inches for the CM10.
Why is the semi-auto load different from the bolt action load?
It is loaded to 2.790 inches with a propellant configuration that cycles the CM10. The 2.802-inch bolt action load is for the CM7S.
Will it run in an AR15?
No. An AR15 accepts cartridges up to 2.260 inches. This load needs an AR10-pattern rifle configured for 458 SOCOM XL, such as the CM10.
Does 458 SOCOM XL use a different chamber?
No. The chamber and case are standard 458 SOCOM. XL names the projectile and the loaded ammunition.
How fast is it?
About 1,012 fps and about 1,478 ft-lb at the muzzle from a 12.5-inch CM10 barrel.
What magazine does it need?
The 458 SOCOM XL magazine, a modified MDT metal magazine configured for 458 SOCOM XL.
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