The .458 SOCOM (11.63×40mmRB) is a moderately large round designed to work in an AR-15 platform. This is achieved by installing a 458 bolt and barrel. The round offers a muzzle velocity of and , similar to a light .45-70 but with a much smaller case.

History

Prompted by the lack of power offered by the 5.56 NATO cartridge used in the

M4 carbine The M4 carbine (officially Carbine, Caliber 5.56 mm, M4) is a 5.56×45mm NATO assault rifle developed in the United States during the 1980s. It is a shortened version of the M16A2 assault rifle. The M4 is extensively used by the US mi ...

and the

M16 rifle The M16 (officially Rifle, Caliber 5.56 mm, M16) is a family of assault rifles adapted from the ArmaLite AR-15 rifle for the United States Armed Forces, United States military. The original M16 was a 5.56×45mm NATO, 5.56×45mm automatic ...

, the .458 SOCOM came about from informal discussion of members of the

special operations Special operations or special ops are military activities conducted, according to NATO, by "specially designated, organized, selected, trained, and equipped forces using unconventional techniques and modes of employment." Special operations ma ...

command Command may refer to: Computing * Command (computing), a statement in a computer language * command (Unix), a Unix command * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on A ...

, specifically

Task Force Ranger Task may refer to: * Task (computing), a unit of execution or homeworks * Task (language instruction) refers to a certain type of activity used in language instructional design * Task (project management), an activity that needs to be accomplis ...

's experience that multiple shots were required to incapacitate members of the opposing force in

Mogadishu Mogadishu, locally known as Xamar or Hamar, is the capital and List of cities in Somalia by population, most populous city of Somalia. The city has served as an important port connecting traders across the Indian Ocean for millennia and has ...

during

Operation Gothic Serpent Operation Gothic Serpent was a military operation conducted in Mogadishu, Somalia, by an American force code-named ''Task Force Ranger'' during the Somali Civil War in 1993. The primary objective of the operation was to capture Mohamed Farra ...

. Marty ter Weeme of Teppo Jutsu and Tony Rumore of Tromix designed the cartridge in 2000 and Tromix was contracted to build the first .458 SOCOM rifle in February 2001. The project sponsor set forth a number of requirements including that the cartridge fit in the

and be capable of firing heavy-for-caliber projectiles at subsonic velocity using suppressors. During the development phase, various other cartridges were considered and proposed to the project sponsor, but rejected as not meeting all the requirements. The cartridges considered were

7.62×39mm The 7.62×39mm (also called 7.62 Soviet, formerly .30 Russian Short) round is a rimless bottlenecked intermediate cartridge of Soviet origin. The cartridge is widely used due to the global proliferation of the AK-47 rifle and related Kalashn ...

9×39mm The 9×39mm is a Soviet rifle cartridge. The cartridge yields increased performance in shorter barrels and effective subsonic performance. History and design The 9×39 is based on the Soviet 7.62×39mm case but with the neck expanded to fit a ...

Grom, .45 Professional (which has since become the .450 Bushmaster), and .50 Action Express. At the time, the .499 LWR cartridge was still in the development phase and had not been chambered commercially. The .45 Professional was ruled out because, in an interview with industry press, the developer of said cartridge stated that steel proprietary to

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

was used in the bolts and extractor to withstand the high operating pressures. The .50 AE and .499 LWR were ruled out because in 2000 only two bullets were offered in .501 diameter, both developed as pistol bullets for the .50 AE and not heavy enough for the subsonic suppressed role. Research had indicated that a short belted cartridge called the .458 × 1.5" Barnes had been adopted for use in suppressed bolt-action rifles for use in South East Asia during the

Vietnam War The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam w ...

. It was shown as effective in terms of ballistics, firing a 500-grain bullet subsonically, but not ideally suited for its role due to the size and weight of the platform. Combined with the wide selection of bullets available in .458 diameter, this cemented the choice of caliber. The cartridge case design was finalized based on discussions with Tony Rumore at Tromix suggesting a lengthened .50 AE case would work well in the magazines as well as be the largest diameter case that could feed through the barrel extension. The initial prototype brass still bore the .50 AE head stamp and this has caused some confusion, as the SOCOM case is longer with a narrower rim. The .50 AE rim diameter was reduced from .514 inch to .473 inch for compatibility with other platforms, primarily bolt-action rifles. The .473-inch/12mm-diameter rim was designed in 1888 for the German Commission Rifle chambered in 7.92×57mm Mauser cartridge, and is arguably the most common rim size globally, as all bolt actions chambered in cartridges derived from that shell, such as

.30-06 Springfield The .30-06 Springfield cartridge (pronounced "thirty- aught-six" ), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military us ...

, .308 Winchester and cartridges derived from them, share this rim size. The case length was chosen to be compatible with the Barnes 300-grain X

Spitzer Spitzer is a surname. Notable people with the surname include: * Andre Spitzer (1945–1972), Israeli fencing coach and victim of the Munich massacre * Bernard Spitzer (1924–2014), American real estate developer and philanthropist, father of E ...

bullet. The final case design has base and rim dimensions identical to the .425 Westley Richards, although making .458 SOCOM cases from it is impractical due to the high cost of .425 brass. In 2009, Barnes developed a new bullet specifically for use in the .458 SOCOM, the 300 grain Tipped Triple Shock X, also known as the TTSX or TAC-X. As noted above, the cartridge was designed to be 100% compatible with the M4 platform. This included the buffer, buffer spring, NATO magazines, many aftermarket .223/5.56 magazines, and magazine well. In .223/5.56 caliber, cartridges stack in a staggered (double stack) fashion. However, with the much larger .458 SOCOM, rounds "single stack" without any modification to the standard GI magazine feed lips or follower. A standard 20-round 5.56mm NATO magazine can hold seven .458 SOCOM rounds and a standard 30-round 5.56mm NATO magazine can hold ten .458 SOCOM rounds.

References

External links

Southern Ballistic Research
* Ralph M. Lermayer
military.com
The website dedicated to the .458SOCOM, where load data and other info also available.
.458 SOCOM Forums
{{Rebated rim cartridges Rebated rim cartridges

458 SOCOM __NOTOC__ Year 458 ( CDLVIII) was a common year starting on Wednesday of the Julian calendar. At the time, it was known as the Year of the Consulship of Maiorianus and Leo (or, less frequently, year 1211 ''Ab urbe condita''). The denominatio ...

History

See also

References

External links