M-150 Battle Rifle

The Hellfocker M-150 Battle Rifle, officially designated Rifle, Caliber 7.62mm, Model 150 is a full-caliber, semi-automatic or select-fire battle rifle designed and produced by the Hellfocker Arms Corporation, a Terran Inner Colonies armaments manufacturer. Introduced in 2667 during Great War, it was adopted by Marine forces and special operations units as a high-quality full-caliber service weapon, easily modified for a variety of tasks. The M150 was introduced into general service, becoming the Army service weapon in 2673 and reaching peak general circulation in 2678. It was gradually replaced in general use in the 2680s by the Mk 78 Icarus Rifle, but this changed due to the Rim War and the experience of Union forces against guerillas fighting at considerable range. An upgraded version, the M150A2, was issued as the infantry service rifle in 2691 across all services, though the Mk 78 has been retained for urban warfare and reserve units.
The M150 is chambered in 7.62x51mm ISTO rounds, a military cartridge standardized in the Interstellar Treaty Organization at the behest of the Terran Empire in 2550, based off the Terran standard rifle round. The 7.62mm round was standardized across human space. Most Terran service rifles since then have used the 7.62x51mm round, whereas most assault rifles have been chambered in 7.62x33mm.
The M150 has been noted as one of the most successful and effective rifles in the past century, renowned for its reliability and versatility.