The 376 Steyr rifle cartridge was developed in collaboration with Hornady Manufacturing, Steyr-Mannlicher, and Lt. Colonel Jeff Cooper's design philosophies for use in the Steyr Scout rifle. It was first released in 1999 and was designed specifically for as an African game legal cartridge. The 376 Steyr used a 9.364mm Brenneke case that had been necked up to receive a 0.375-inch (9.5 mm) bullet. To suit a normal length rifle action, the casing is additionally reduced by around 4 mm. The 376 Steyr was also chambered in the Steyr Prohunter rifle for a brief period, however this combination was abandoned.
Because the 376 Steyr is a long cartridge for a short action rifle, it can only be loaded in short action rifles with long (modified) magazines. When velocity is low in a medium bore, the performance window might be rather small. Most medium bore bullets perform admirably at impact speeds of 2200 feet per second. Shot location becomes increasingly critical between 2200 and 1800 frames per second. Bullet expansion can be poor below 1800fps. This style of load is ideal for hunting medium game in the bush or forests, since it allows for quick kills. When hunting extremely large game, however, the 376 Steyr has limits.
On heavy animals, a robust medium weight (250 grain) bullet might be the most efficient killer, but the hunter should not anticipate quick results. Kills can take more than a minute (often considerably longer) unless the hunter uses careful CNS shots, allowing large animal to move a lot of area before falling from blood loss.
