The .458 SOCOM (11.63×40mm) was designed and developed by Marty ter Weeme of Teppo Jutsu, LLC in 2000. The 458 SOCOM cartridge is a moderately large round designed for modified AR-15 upper receivers that can be mounted on any AR-15 pattern lower receiver. The 300-grain (19 g) round offers a muzzle velocity of 1,900 ft/s. Currently more than a dozen rifle makers offer production firearms in this caliber.
