The .300 Remington Ultra Mag
By Chuck Hawks
In 1999 Remington brought out the beltless .300 Ultra Mag in their Model 700 rifle. It is loosely based on a blown out and necked down .404 Jeffery case with a 30 degree shoulder. This is a very large rimless bottleneck case that, with factory loads, only manages to duplicate the performance of the .300 Weatherby Magnum.
The .300 Ultra has a rebated rim that allows the body of the case to be fatter than the rim, which is the same size as the rim on standard belted magnum cases. This allows it to work with standard diameter magnum bolt faces, at the price of potentially reduced feeding reliability. This is because with a rebated rim there is less rim area for the bolt to catch as it tries to push a cartridge from the magazine and into the chamber.
No cartridge with a rebated rim is a good candidate for use on dangerous game, where a failure to feed could be fatal. The .300 Ultra Mag should be confined to use on large non-dangerous game like elk and moose.
The .300 Ultra's case has a rim diameter of .534 inch and a body diameter at the base of .550 inch, tapering slightly to a shoulder diameter of .525 inch. It is 2.85 inches long (the same as the old .375 H&H), and it will hold 112 grains of water. Maximum cartridge length is 3.6 inches.
This monster has 20% more powder capacity than the .300 Win. Mag. and 13% more capacity than the .300 Weatherby Mag. It is reportedly loaded to a maximum average pressure of 52,000 cup.
Barrels should be at least 26 inches long or the performance falls back to standard length .300 Magnum levels. 28 or 30 inch barrels are even better for a .300 Ultra Mag rifle. As I write this, Remington Model 700 rifles in this caliber are supplied with 26" barrels.
American Rifleman magazine reported that their Model 700 test rifle in .300 Ultra Mag with a 4-12 power scope, sling, and 4 rounds of ammunition weighed 8.25 pounds. That is much too light for a rifle chambered for so powerful a cartridge. The "Rifle Recoil Table" on the Rifle Information Page shows that an 8.25 pound .300 Ultra Mag rifle slams the shooter's shoulder with 38.4 ft. lbs. of recoil energy!
Remington and Federal offer factory loads with 180 grain bullets (SD .271) at a muzzle velocity (MV) of 3,250 fps and muzzle energy of 4221 ft. lbs. Remington's 200 yard figures for the Nosler Partition spitzer bullet are 2834 fps and 2503 ft. lbs.
Remington also offers a 150 grain Swift Sirocco bullet (SD .226) at a MV of 3450 fps with ME of 3964 ft. lbs. The 200 yard numbers are 2980 fps and 2956 ft. lbs. This bullet seems pretty light for such a big case, but qualifies the .300 Ultra as an ultra-long range cartridge, which is probably the point of the exercise.
More useful is the load Remington offers with a 200 grain Nosler Partition bullet (SD .301) at a MV of 3,025 fps and ME of 4063 ft. lbs. At 200 yards the figures are 2636 fps and 3086 ft. lbs. This is the factory load to choose for moose and other very heavy game. The trajectory of that load is as follows (Remington figures): +2.4" at 100 yards, +2" at 200 yards, 0 at 250 yards, -3.4" at 300 yards, and -14.6" at 400 yards.
150 and 165 grain bullets appear to be of limited usefulness in such a large case. The 180 and 200 grain bullets are fine as far as they go, but even heavier bullets would seem appropriate. Remington should offer a 220 grain factory load for the .300 Ultra Mag.
The handloader can use the entire range of .30 caliber bullet weights in the .300 Ultra Mag, and can duplicate the factory loads with heavy charges of appropriate slow burning powders. No doubt the all-around bullet weight of 180 grains will prove the most popular with reloaders just as it has with those who buy factory loads.
According to the fifth edition of the Nosler Reloading Guide, a 150-155 grain Nosler bullets can be driven to a MV of 3380 fps by 98.0 grains of Hodgdon's H1000 powder, or a MV of 3513 fps by 102.0 grains of H1000 powder. Nosler data shows that their 180 grain bullets can be driven to a MV of 3089 fps by 92.0 grains of H1000, or a velocity of 3225 fps by 96.0 grains of H1000 powder. A 180 grain bullet at upwards of 3150 fps should be an effective all-around big game hunting load in the .300 Ultra Mag.
The Nosler 200 grain Partition spitzer bullet can be driven to a velocity of 3090 fps by a maximum load of 104.0 grains of H870 powder. And the heavy 220 grain Partition Semi-spitzer can achieve a MV of 2987 fps in front of a maximum load of 102.0 grains of H870 powder. All of these Nosler loads used Remington cases and Federal 215 primers and were tested in a 26" barrel.
The trajectory figures for a 180 grain spitzer bullet at a MV of 3250 fps should look about like this: +2.4" at 100 yards, +3" at 155 yards, +2.6" at 200 yards, and -3" at 320 yards. This shows that the .300 Ultra is indeed an ultra-long range cartridge.
For decades Remington had yearned for a .300 Magnum cartridge with their name on the head stamp. But with the standard length .300 Winchester Magnum and the full length .300 Weatherby Magnum well established and at the height of their popularity, Remington felt effectively shut out of the game. Eventually the demand for ever higher velocity gave Remington the opening they needed and the redundant .300 Ultra Mag is the result.
Copyright 2003, 2012 by Chuck Hawks. All rights reserved.