458 SOCOM vs 450 Bushmaster is, for suppressed shooting, a question of how much bullet each can fire below the speed of sound. The common 450 Bushmaster subsonic load is a 395 gr Sub-X loaded to fit an AR15 magazine. Chattahoochee Munitions loads 458 SOCOM XL beyond that AR15 limit with a 650 gr Maker REX, 255 grains heavier, and manufactures the CM7S bolt action and CM10 semi-automatic firearms configured to fire it. From a 12.5-inch barrel the 650 gr load carries about 1,473 ft-lb at the muzzle, about 50 percent more than the 395 gr Sub-X’s published 967 ft-lb from a 24-inch test barrel.
458 SOCOM vs 450 Bushmaster Subsonic at a Glance
| 458 SOCOM XL, 650 gr REX | 450 Bushmaster, 395 gr Sub-X | |
|---|---|---|
| Bullet diameter | .458 in | .452 in |
| Bullet weight | 650 gr | 395 gr |
| Bullet construction | Solid copper expanding, lead free | Jacketed expanding with a flexible tip |
| Ballistic coefficient (G1) | .44 | About .300 |
| Sectional density | .443 | About .276 |
| Muzzle velocity | About 1,010 fps (CM7S) and 1,012 fps (CM10), measured from 12.5-inch barrels | 1,050 fps published, from a 24-inch test barrel |
| Muzzle energy | About 1,473 ft-lb | 967 ft-lb published |
| Overall length | 2.802 in (CM7S), 2.790 in (CM10) | 2.260 in (AR15 limit) |
| Firearms | CM7S short action, CM10 AR10 pattern | AR15 and some bolt actions |
458 SOCOM vs 450 Bushmaster: Why Bullet Weight Decides Subsonic Performance
A subsonic bullet must stay below the speed of sound, about 1,050 to 1,116 fps depending on temperature. With velocity capped, the only way to carry more energy is a heavier bullet. At almost the same speed, the 650 gr REX outweighs the 395 gr Sub-X by about 65 percent, and its energy follows its weight.
Weight also drives retained energy and penetration. The 650 gr REX has a sectional density of .443 and a ballistic coefficient of .44 G1, against about .276 and .300 for the 395 gr Sub-X, so it loses velocity more slowly and carries more momentum into the animal. From a 12.5-inch barrel, the 650 gr load still carries about 1,342 ft-lb at 100 yards, well above the 395 gr Sub-X’s published muzzle energy.
458 SOCOM vs 450 Bushmaster: The AR15 Limit Both Share
458 SOCOM and 450 Bushmaster were both designed to fit the AR15, which caps each at 2.260 inches overall. That cap limits subsonic bullet weight, because a long, heavy bullet has to sit deep in the case and take up powder space. The 450 Bushmaster’s longer 1.700-inch case leaves even less room above it for bullet length than 458 SOCOM’s 1.575-inch case, which keeps its common subsonic bullet near 395 gr.
458 SOCOM XL moves past that cap. Chattahoochee Munitions loads the 2.035-inch, 650 gr projectile in factory-new Starline 458 SOCOM brass to 2.802 inches for the CM7S and 2.790 inches for the CM10. Seating it less deeply reclaims case capacity for powder. The chamber and case stay standard 458 SOCOM, designed in 2000 by Marty ter Weeme of Teppo Jutsu; the firearm and its modified MDT metal AICS-pattern magazine are configured for XL length.
458 SOCOM vs 450 Bushmaster: Barrel Length and Velocity
Published factory velocities come from test barrels, and the 395 gr Sub-X’s 1,050 fps figure comes from a 24-inch barrel. Shorter AR15 barrels produce less. The Chattahoochee Munitions 650 gr figures were measured from 12.5-inch barrels, the length its suppressed CM7S and CM10 SBRs use, so they reflect what a short-barrel shooter sees. At about 1,010 fps, the 650 gr load stays below the speed of sound even at 0°F, where sound travels about 1,051 fps. Full figures are in 458 SOCOM ballistics.
458 SOCOM vs 450 Bushmaster for Suppressed Hunting
In 458 SOCOM vs 450 Bushmaster subsonic loads, both bullets are designed to expand at low velocity, and both suit hogs and deer at known, moderate distances. The difference is margin. The 650 gr solid copper REX carries about 1,342 ft-lb at 100 yards, enough for large hogs and any North American bear, and Maker states that REX projectiles expand to nearly three times their original diameter while keeping nearly all of their weight. Read 458 SOCOM hunting and 458 SOCOM for bear.
With subsonic ammunition, use an enclosed suppressor rated for the caliber: .458 for 458 SOCOM, and .452 or larger for 450 Bushmaster. Chattahoochee Munitions recommends an enclosed suppressor on both the CM7S and the CM10; the 12.5-inch CM7S is also offered with the all-titanium PLACID OTB. See the 458 SOCOM suppressor guide.
458 SOCOM vs 450 Bushmaster Supersonic
With supersonic ammunition the two are close. A 250 gr 450 Bushmaster at about 2,200 fps produces roughly 2,690 ft-lb, and a 250 gr 458 SOCOM at about 2,150 fps produces roughly 2,570 ft-lb, both from AR15s. Supersonic loads shoot flatter but make a crack downrange that no suppressor removes, which is why Chattahoochee Munitions focuses on heavy subsonic 458 SOCOM XL.
458 SOCOM vs 450 Bushmaster: Which Should You Choose?
- Choose 450 Bushmaster for supersonic deer loads in an AR15, or a 395 gr subsonic in a rifle you already own.
- Choose 458 SOCOM XL for 650 gr suppressed subsonic shooting, about 50 percent more muzzle energy than the 395 gr Sub-X’s published figure, from a CM7S bolt action or CM10 semi-auto with a 12.5-inch or 16-inch barrel.
Compare the two Chattahoochee Munitions platforms in 458 SOCOM bolt action vs semi auto, and see every configuration on Terminal 458.
458 SOCOM XL Firearms
For shooters settling 458 SOCOM vs 450 Bushmaster in favor of heavy subsonic, these are the options.
Chattahoochee Munitions manufactures complete factory firearms chambered in 458 SOCOM and configured for 458 SOCOM XL:
- CM7S 458 SOCOM 12.5-inch SBR with PLACID OTB
- CM7S 458 SOCOM 12.5-inch bolt action pistol or SBR
- CM7S 458 SOCOM 16-inch bolt action rifle
- CM10 458 SOCOM 12.5-inch semi-automatic SBR
- CM10 458 SOCOM 16-inch semi-automatic rifle
458 SOCOM vs 450 Bushmaster FAQ
Which is better for subsonic, 458 SOCOM or 450 Bushmaster?
458 SOCOM accepts heavier bullets. Chattahoochee Munitions 458 SOCOM XL fires a 650 gr REX at about 1,473 ft-lb from a 12.5-inch barrel; the common 450 Bushmaster subsonic load is a 395 gr Sub-X with a published 967 ft-lb from a 24-inch barrel.
How heavy is 450 Bushmaster subsonic ammunition?
The common 450 Bushmaster subsonic load uses a 395 gr Sub-X bullet, with a published 1,050 fps from a 24-inch test barrel.
How much energy does 458 SOCOM subsonic have compared to 450 Bushmaster?
The 650 gr 458 SOCOM XL load carries about 1,473 ft-lb at the muzzle and about 1,342 ft-lb at 100 yards. The 395 gr 450 Bushmaster Sub-X is published at 967 ft-lb at the muzzle.
Is 458 SOCOM the same bullet diameter as 450 Bushmaster?
No. 458 SOCOM uses .458-inch bullets and 450 Bushmaster uses .452-inch bullets, so the bullets are not interchangeable.
Why can 458 SOCOM XL use a 650 gr bullet?
It is loaded to 2.802 inches (CM7S) or 2.790 inches (CM10) instead of the AR15’s 2.260 inches, so the 2.035-inch projectile sits less deeply and leaves room for powder.
Which hits harder with supersonic loads?
They are close: about 2,570 ft-lb for a 250 gr 458 SOCOM and about 2,690 ft-lb for a 250 gr 450 Bushmaster.
Who makes a 458 SOCOM rifle that is not an AR15?
Chattahoochee Munitions manufactures the CM7S short-action bolt action and the CM10 AR10-pattern semi-auto in 458 SOCOM, both configured for 458 SOCOM XL.