The 458 SOCOM (aka: 11.5x40mm RB) is a large caliber cartridge designed for use on the AR15/M4 platform. It was developed by Marty ter Weeme, founder of Teppo Jutsu LLC in 2000. The impetus was an informal ("beer and barbeque") discussion with a senior member of the US special operations community regarding the apparent lack of effectiveness of the 5.56 x 45 rifle cartridge in a recent conflict. In particular, the reports from members of Task Force Ranger in Mogadishu, Somalia as part of Operation Gothic Serpent that multiple shots were required to neutralize members of the opposing force led to the request to develop a new cartridge that would deliver far more energy from short barrels at relatively short distances.
After the design was completed, Tony Rumore of Tromix Corp in Broken Arrow, OK was contacted to build the first prototype. Based on the favorable reviews, commercial production was started and the initial rifles were produced by Tromix. Marty contacted me, Buddy Singleton, at Southern Ballistic Research, LLC (SBR) in Brunswick, GA, and asked me to develop factory loaded ammunition for the 458 SOCOM. Today, we are the leading manufacturer of factory loaded 458 SOCOM with over 22 different loads available. SBR continues the ballistic research to help take the 458 SOCOM cartridge to the next step as a fully developed CQB weapons platform. In addition to law enforcement and military applications, 458 SOCOM ammo has become a very popular hunting cartridge for medium and large game. Also, in late 2020, the CIP Committee reached out to SBR about the 458 SOCOM, and in November 2021 the 458 SOCOM was CIP approved. You can download a copy of the cartridge print directly from the CIP website, or click here to download a pdf copy.