The .300 Remington Short Action Ultra Magnum (RSAUM) is a centerfire rifle cartridge developed by Remington Arms in 2001. It is designed for use in short-action rifles, offering magnum-level performance in a more compact case. The cartridge has a case length of 2.015 inches and can achieve velocities similar to the .300 Winchester Magnum but in a shorter, more efficient case, which allows for reduced rifle weight and potentially better handling.
The .300 RSAUM is suitable for a variety of big game hunting, including deer, elk, and moose, due to its high velocity and energy, which translate to effective terminal performance at various ranges. Bullet weights for this cartridge typically range from 150 to 200 grains, allowing for flexibility depending on the type of game being hunted and the shooting conditions.
This cartridge is known for its accuracy and has a relatively flat trajectory, made possible through the use of modern powders and bullet designs. It's popular among hunters and long-range shooters looking for a balance of power and manageability in a short-action rifle platform.