The .300 RUM, which stands for Remington Ultra Magnum, was
first introduced by Remington Arms in 1999. Also known as the
.300 Ultra Mag,
.300 RUM has become one of the largest commercially available .30 caliber
magnums currently being produced. It features a
beltless, rebated rim cartridge
and is extremely capable of handling all large game animals in North America,
and works exceptionally well for long-range shots.
In the early 1980s Aubrey White and Noburo Uno of North American
Shooting Systems (NASS) based in British Columbia Canada began experimenting
with the full length
.404 Jeffery by reducing the taper and necking
it down to various calibers such as 7 mm, .308, 311, 338, 9.3 mm and
.375. These cartridges were known variously as the Canadian Magnum or the
Imperial Magnums. Rifles were built on Remington Model 700 Long
Actions and used McMillan stocks. Cartridges were fire formed from
Jeffery cases with the rim turned down, taper reduced and featured sharp
Both Remington and Dakota Arms purchased the formed brass designed by
Uno for use in their own experimentation and cartridge development. In
1999 Remington released the first of a series of cartridges virtually identical
to the Canadian Magnum cartridges which featured a slightly wider body,
increased taper, and shallower shoulders and named it
the .300 Remington Ultra
Magnum. Dakota too released their own version of the
cartridge, but chose not to
turn down the rim and shortened the case to work in a standard-length action.
Each box contains 25 once fired brass shell casings. All Remington-Peters (RP) headstamps. This is unprocessed brass sourced from commercial shooting ranges. The casings have been washed and polished, but not resized and may still contain the spent primer.
It is recommended that all brass be inspected prior to being reloaded and fired.