While the U.S. Army and the U.S. Special Operations Command (USSOCOM) are introducing new rifles and calibers such as the M7 in 6.8 mm Common Cartridge and the Mk24 in 6.5 mm Creedmoor, at least the latter also intends to further develop the traditional M4 carbine in 5.56 x 45 mm NATO. Thus the command recently launched a tender under the designation Hypervelocity Improved Carbine (HICAR) for an M4 upper receiver from which “upcoming hypervelocity ammunition” can be fired.
This ammunition is designated M855A1+, i.e., a more heavily loaded version of the current service cartridge, intended to double the effective combat range from 300 to at least 600 meters. Through advanced materials usage, it is intended to achieve chamber pressures of 82,000 psi compared to the previously typical 55,000 psi. In testing, 600 rounds are to be fired using the new upper receiver, predominantly using the stronger ammunition.
Introduction to USSOCOM in Mid-September
Recently the ammunition manufacturer Federal Ammunition had already reached an agreement with the U.S. Army to use its “Peak Alloy” case technology. According to the manufacturer, this is an alloy of high-strength steel that enables chamber pressures of over 80,000 psi. It was commercially introduced with the 2024-developed 7 x 61 mm Backcountry load. It is based on the case of the former American military cartridge .30-06 Springfield, but with a bullet weight of ten grams achieves a muzzle velocity of 1,000 rather than 890 meters per second.
The muzzle energy rises accordingly from under 4,000 to 5,000 joules. An increase would also be expected for the 5.56 x 45 mm cartridge. The agreement between Federal and the U.S. Army provides for the use of Peak Alloy in calibers up to .50 BMG (12.7 x 99 mm). For the HICAR program bids are to be submitted by June 8, and on September 15 and 16 the concepts for the new upper receiver are to be presented to USSOCOM.
