.300 Rem. SA Ultra Mag. Load Data

Caliber Overview

Introduced in the early 2000s, the .300 Remington Short Action Ultra Magnum, commonly known as .300 Rem. SA Ultra Mag, marked a significant point in the evolution of high-performance cartridges suited for short-action rifles. Developed by Remington Arms, this caliber was engineered to coexist with the popularity of the Winchester Short Magnum line, offering magnum ballistics in a more compact package. The .300 Rem. SA Ultra Mag's design is based on a shortened .404 Jeffery case, intended to maximize powder capacity while allowing use in short-action rifles, making it a direct competitor to the .300 Winchester Short Magnum (WSM). Its introduction responded to the desire among shooters and reloaders for magnum-level performance in a lighter, more maneuverable rifle platform—without the need for longer, heavier actions.

For reloaders, the .300 Rem. SA Ultra Mag presents a versatile option suitable for a range of shooting pursuits, including big-game hunting, long-range target shooting, and even tactical applications. Its balanced design achieves high velocities and impressive downrange energy, making it a favorite among hunters seeking a flat-shooting, hard-hitting caliber. The short-action configuration allows for quicker cycling and marginally lighter rifles, which is beneficial when stalking game across rugged terrain or engaging in dynamic shooting disciplines. Competitive shooters also appreciate the round’s accuracy and consistent performance at extended distances, attributed to the caliber's efficient case design and favorable ballistic profile.

When choosing the .300 Remington SA Ultra Mag for hunting, most reloaders and shooters look to pursue a variety of North American big-game animals, such as elk, moose, mule deer, and black bear. The caliber’s high velocity and energy are more than adequate for ethical, long-range shots on large-bodied game. It also sees some use in African plains game hunting, where its performance ensures reliable penetration and expansion. While its power may be more than necessary for smaller deer species or varmints, the caliber’s flat trajectory assists shooters in making precise shots across variable distances, reducing the need for constant holdover adjustments.

Regarding bullet weights and characteristics, the .300 Rem. SA Ultra Mag supports a wide range of projectile options, catering to specific reloading needs and target species. Typical bullet weights range from 150 grains for lighter, flatter-shooting loads, up to 220 grains for maximum penetration on the largest game. Most reloaders find that bullets in the 165–180 grain range offer an optimal balance of velocity and terminal performance for general big-game hunting. In addition to impressive velocities—often exceeding 3,100 fps with 150-grain bullets—the caliber is known for producing high muzzle energy and maintaining excellent performance at extended ranges. The straight-walled, rebated rim design of the cartridge promotes reliable feeding, while the relatively short case ensures compatibility with a wide array of short-action rifle platforms. Its magnum-level recoil is noticeable, but generally manageable with proper rifle design and shooting technique, rounding out a caliber that remains a strong choice for reloaders seeking flexibility, power, and performance in the field or at the range.