The .300 Remington Ultra Magnum
, also known as the .300 Ultra Mag
' or .300 RUM
is a 7.62 mm (.308in.) caliber rifle cartridge , 7.62x72mm
, or .30 caliber rifle
A rifle is a firearm designed to be fired from the shoulder, with a barrel that has a helical groove or pattern of grooves cut into the barrel walls. The raised areas of the rifling are called "lands," which make contact with the projectile , imparting spin around an axis corresponding to the...
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...
introduced by Remington Arms
Remington Arms Company, Inc. was founded in 1816 by Eliphalet Remington in Ilion, New York, as E. Remington and Sons. It is the oldest company in the United States which still makes its original product, and is the oldest continuously operating manufacturer in North America. It is the only U.S....
in 1999. The .300 Remington Ultra Magnum is one of the largest commercially available .30 caliber magnums currently being produced. It is a beltless, rebated rim cartridge, capable of handling all large North American game, as well as long-range shooting. Among commercially-produced .30-caliber rifle chamberings, The .300 Remington Ultra Magnum is second only to the .30-378 Weatherby Magnum
The .30-378 Weatherby Magnum is a cartridge introduced by Weatherby in 1996 that uses the same case as the previously existing .378 Weatherby Magnum and .460 Weatherby Magnum, necked down to a 30 caliber bullet. It is offered with bullets between 165 and 200 grains in factory loading, generating...
in cartridge-case capacity.
Origin & History
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
The .404 Jeffery is a large caliber, rimless cartridge designed for large, dangerous game, such as the big five of Africa. Other names for this cartridge include .404 Jeffery Rimless, .404 Rimless Nitro Express, and 10.75 × 73 mm...
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
The Model 700 series of firearms are bolt-action rifles manufactured by Remington Arms since 1962. All are based on the same centerfire bolt action. They often come with a 3, 4 or 5-round internal magazine depending on caliber, some of which have a floor-plate for quick-unloading, and some of which...
and used Macmillan stocks. Cartridges were fire formed from .404 Jeffery cases with the rim turned down, taper reduced and featured sharp shoulders.
Both Remington and Dakota Arms purchased the formed brass designed by Noburo 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. Remington would go on to design their own shortened versions of the Ultra Magnum cartridge which they were to call the Remington Short Action Ultra Magnum or RSAUM for short.
Design & Specification
The .300 Remington Ultra Magnum is a member of the Remington Ultra Magnum cartridge family based on the .404 Jeffery via the Canadian Magnum cartridges. As these cartridges feature wider bodies than the belted magnums based on the .375 H&H
The .375 Holland & Holland Magnum is a powerful rifle round and one of the best-known and most popular medium-bore cartridges in the world. The .375 H&H was only the second cartridge ever to feature a belt, now common among magnum rounds. A popular misconception is that the belt is for headspace,...
case, these cartridges have greater case capacities than their corresponding full length belted Magnum cartridges such as the 7 mm Shooting Times Westerner
The 7mm Shooting Times Westerner, sometimes refereed to as the 7mm STW began as a wildcat rifle cartridge developed by Layne Simpson in 1979. It is an 8 mm Remington Magnum case that has been "necked down" by 1 mm to accept 7 mm bullets...
, the .300 Weatherby Magnum
The .300 Weatherby Magnum is a .30 caliber rifle cartridge created by Roy Weatherby in 1944 and produced by Weatherby. It has become the most popular of all the Weatherby cartridges.-Background:...
, .340 Weatherby Magnum
The .340 Weatherby Magnum rifle cartridge was introduced in 1963 by creator Roy Weatherby in response to the .338 Winchester Magnum. The .340 Weatherby Magnum uses the same .338 in. diameter bullets as the .338 Winchester Magnum but it does so at greater velocity than its Winchester competition...
and the .375 Ackley Improved.
The .300 RUM features a rebated rim much like the .300 Canadian Magnum so as to allow the cartridge to function in the Remington M700 action without having to increase the bolt and bolt face diameter of the action. The down side is this may result in feeding failures and over-ride jams as the cartridge is cycled into the chamber and is considered undesirable in a dangerous game cartridge. Unlike the belted Magnum cases based on the .375 H&H Magnum cartridge, the .300 RUM does not have a belt. All things being equal, a beltless cartridge would feed more reliably and more smoothly than a belted cartridge. Furthermore, as this is a beltless cartridge headspacing is designed to take place on the shoulder, which is considered beneficial by some as it is thought to promote accuracy and prolong case life of the cartridge.
- SAAMI compliant .300 Remington Ultra Magnum cartridge schematic: All dimensions in inches [millimeters].
The Sporting Arms and Ammunition Manufacturers' Institute is an association of American firearms and ammunition manufacturers...
recommends that the barrel have a 6 groove contour with a twist rate of one revolution in 10 in (254 mm). The barrel is to have a groove width of 0.115 in (2.9 mm). Bore is given as 0.3 in (7.6 mm) and a groove is 0.308 in (7.8 mm). Maximum case overflow capacity is 122.5 gr. of water (7.30 cm3
). SAAMI recommended Maximum Average Pressure is set at 65000 psi (4,481.6 bar).
Remington’s ultra magnum cases were made wider than the .404 Jeffery case by 0.006 in (0.1524 mm). The brass was made thicker so as to withstand the higher pressure of the new cartridge as the Jeffery cartridge had a maximum average pressure rating of 3650 bar (52,938.8 psi).
Remington ammunition for the .300 RUM is available in three Power Levels. Power Level I duplicates the .30-06 Springfield, Power Level II that of the .300 Winchester and Power Level III is the full power load. Remington offers the full power (Power Level III) .300 Remington Ultra Magnum ammunition in 150 gr at 3450 ft/s (1,051.6 m/s), the 180 gr at 3250 ft/s (990.6 m/s) and the 200 gr at 3032 ft/s (924.2 m/s). These are among the highest velocities attained by a .30 caliber production rifle cartridge.
Performance Characteristics .300 Remington Ultra Magnum Power Level III Ammunition
|| 100 yards (91.4 m)
|| 200 yards (182.9 m)
|| 300 yards (274.3 m)
|| 400 yards (365.8 m)
|| 500 yards (457.2 m)
| Premier Scirocco Bonded 150 gr PR300UM5
|| 3450 ft/s (1,051.6 m/s)
|| 3211 ft/s (978.7 m/s)
|| 2985 ft/s (909.8 m/s)
|| 2769 ft/s (844 m/s)
|| 2564 ft/s (781.5 m/s)
|| 2369 ft/s (722.1 m/s)
|| 3964 ft·lbf (5,374.5 J)
|| 3434 ft·lbf (4,655.9 J)
|| 2967 ft·lbf (4,022.7 J)
|| 2554 ft·lbf (3,462.8 J)
|| 2190 ft·lbf (2,969.2 J)
|| 1869 ft·lbf (2,534 J)
| Bullet Drop
|| -1.5 in
|| 2.6 in (6.6 cm)
|| 3.2 in (8.1 cm)
|| 0 in (0 cm)
|| -7.8 in
|| -20.9 in
| Premier Scirocco Bonded 180 gr PR300UM3
|| 3250 ft/s (990.6 m/s)
|| 3051 ft/s (929.9 m/s)
|| 2860 ft/s (871.7 m/s)
|| 2677 ft/s (815.9 m/s)
|| 2502 ft/s (762.6 m/s)
|| 2334 ft/s (711.4 m/s)
|| 4221 ft·lbf (5,722.9 J)
|| 3719 ft·lbf (5,042.3 J)
|| 3268 ft·lbf (4,430.8 J)
|| 2864 ft·lbf (3,883.1 J)
|| 2501 ft·lbf (3,390.9 J)
|| 2177 ft·lbf (2,951.6 J)
| Bullet Drop
|| -1.5 in
|| 2.9 in (7.4 cm)
|| 3.6 in (9.1 cm)
|| 0 in (0 cm)
|| -8.5 in (-22 cm)
|| -22.5 in
| Premier A-Frame 200 gr RS300UM2
|| 3032 ft/s (924.2 m/s)
|| 2793 ft/s (851.3 m/s)
|| 2566 ft/s (782.1 m/s)
|| 2352 ft/s (716.9 m/s)
|| 2148 ft/s (654.7 m/s)
|| 1954 ft/s (595.6 m/s)
|| 4082 ft·lbf (5,534.4 J)
|| 3464 ft·lbf (4,696.6 J)
|| 2924 ft·lbf (3,964.4 J)
|| 2456 ft·lbf (3,329.9 J)
|| 2049 ft·lbf (2,778.1 J)
|| 1695 ft·lbf (2,298.1 J)
| Bullet Drop
|| -1.5 in
|| 3.7 in (9.4 cm)
|| 4.5 in (11.4 cm)
|| 0 in (0 cm)
|| -10.8 in
|| -29.2 in
| Rifle sighted in 1.5 inch (2.5 cm) above bore axis. Altitude 1000 ft. Temperature 59 °F. Values courtesy of Big Game Info Ballistic Calculator
The .300 RUM is an excellent long range cartridge with the ability to deliver a useful level of energy downrange especially with the power level III ammunition.. Due to its high velocity it exhibits less bullet drop than most other .30 caliber (7.62 mm) cartridges.
Compared to other production .30 caliber (7.62 mm) cartridges, only the .30-378 Weatherby Magnum surpasses the .300 Remington Ultra Magnum. Factory loaded .30-378 Weatherby Magnum ammunition has a 150–200 ft/s (45.7–61 m/s) velocity advantage over the .300 RUM cartridge with any given bullet weight. However, the .30-378 Weatherby Magnum is considered the most overbore production sporting cartridge available and is not considered as efficient as the .300 RUM cartridge which is also one of the most overbore cartridges available.
The .300 Remington Ultra Magnum cartridge was conceived as a long range hunting cartridge and in this it excels over most other cartridges. It is able to launch bullets of good weights and sectional densities at high velocities and remaining energy to take game cleanly at longer ranges than lesser cartridges such as the .30-06 Springfield and even the .300 Winchester Magnum.
It is an excellent one gun cartridge for hunting all North American game species, though the cartridge is considered to be overly powerful for smaller big game species such as pronghorns, white-tail and mule deer. The cartridge comes into its own for larger deer species such as elk and moose. The .300 RUM is considered an excellent cross canyon rifle when hunting in the foothills or the Rockies where the opportunity for long distance shooting can present itself. The cartridge has enough remaining energy at 875 yd (800.1 m) for deer sized game and capable of taking elk sized game out to 700 yd (640.1 m).
Due to the excess power and energy which the cartridge can bring to bear and the very flat shooing capability of the cartridge, the .300 RUM makes a first-rate choice when hunting African plains game especially in the plains and the savannah. With the exception of dangerous game the cartridge would be a good candidate for an all round rifle cartridge for African game species.