7mm Remington Ultra Magnum
Date: Oct 08 2014
Notes from the Lab: 7mm Remington Ultra Magnum
The 7mm Remington Ultra Mag is based on the .300 RUM case necked to 7mm (.284 inch), making it something of an over-bore capacity cartridge. It is advertised to push a 140-grain bullet at 3,425 fps, a 150 at 3,325 fps and a 175-grain bullet at 3,025 fps, which easily outperforms the popular 7mm Remington Magnum. As a result, it offers a flat trajectory that is useful for hunting in open country, or where long shots are common.
Remington is currently offering "Power-Level" (velocity) loads rated I, II or III. The "reduced" loads are carefully tested with powders designed to burn properly in the cartridge’s large case and at lower pressures. Reduced loads are not recommended with any of the powders used in the accompanying chart, or hang-fires and erratic ignition may occur.
Using Hornady 139-grain bullets, Alliant RL-22 and Hodgdon H-1000 powders easily exceeded factory load velocities, while RL-25 produced the highest velocity with 154-, 162- and 175-grain bullets. Large rifle magnum primers are recommended to achieve correct powder ignition, with Federal 215 primers being used herein.