.300 Rem. SA Ultra Mag

The .300 Remington Short Action Ultra Magnum, commonly known as the .300 Rem. SA Ultra Mag or .300 RSAUM, is a relatively recent addition to the lineage of high-powered, short-action rifle cartridges. Introduced by Remington in 2001, this cartridge was part of a trend among ammunition manufacturers to shorten magnum rifle cartridges while maintaining significant power. The .300 Rem. SA Ultra Mag was designed by trimming the original .300 Remington Ultra Magnum case to fit a short-action rifle, thus providing magnum-level ballistics in a shorter, lighter, and often more accurate package. It directly competes with the .300 Winchester Short Magnum (WSM), which Winchester released around the same period. Despite entering a crowded market containing both traditional and newer short magnums, the .300 RSAUM has carved out a niche among reloaders and dedicated shooters looking for performance and versatility in a compact cartridge.

The application of the .300 Rem. SA Ultra Mag in the field is diverse. Its design lends itself well to both hunting and long-range target shooting. With ballistic performance comparable to the venerable .300 Winchester Magnum but in a more compact form, it’s particularly attractive for those wanting to use a short-action rifle platform for increased rigidity and quicker cycling. For reloaders, the cartridge offers the advantage of efficient powder burning and relatively manageable recoil for a magnum cartridge, making it a practical choice for repeated use and experimentation with various handloads. Its consistent velocities and accuracy potential make the .300 RSAUM a favorite among competitive shooters who prioritize precision at extended ranges, as well as hunters needing reliable knock-down power.

When considering target species, the .300 Rem. SA Ultra Mag truly shines as a versatile option for North American game. Ammunition loaded with the correct bullet weights and construction can handle anything from deer and wild hogs up to elk, moose, and even bear. The cartridge’s flat trajectory and energy retention at long distances make it ideal for open-country hunting and mountain terrain where longer shots are expected. Its power is more than adequate for all large game in North America, provided that the shooter selects the right bullet for the job. For reloaders, this adaptability means one well-crafted load can be used for a broad range of hunting situations, reducing the need for multiple rifles or barrel changes.

Typical bullet weights for handloading the .300 Rem. SA Ultra Mag range from 150 grains for lighter, flatter-shooting loads suitable for smaller game and varmints, up to 200 grains or more for heavy, deep-penetrating hunting bullets. The cartridge performs exceptionally well with 165-180 grain bullets, balancing velocity, energy, and trajectory for most big game applications. For target shooters or those pushing long range, premium match-grade bullets in the 175-200 grain range are popular choices, as the cartridge’s case capacity and short, fat design promote efficient powder burn and consistent chamber pressures. The standard case holds approximately 70 grains of powder, depending on the load, and the SAUM’s short action platform reduces bolt throw, improving cycling speed in compatible rifles. The .300 RSAUM’s rebated rim and steep shoulder angle contribute to reliable feeding and excellent case life, both valued by reloaders seeking consistent performance and longevity from their brass. With these characteristics, the .300 Rem. SA Ultra Mag continues to be an attractive, flexible cartridge for avid shooters and reloaders seeking magnum performance without the added length or bulk of traditional long-action cartridges.