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Pick the Best .300 Short Mag

Pick the Best .300 Short Mag

How do the short mags from Winchester, Remington and Ruger stack up?

Usually this column is devoted to a single cartridge, but since the .300 Remington Short Action Ultra Mag, .300 WSM and .300 RCM are pretty much peas in a pod, I thought it might be interesting to compare them.

I will start with Remington's Short Action Ultra Mag. During 1997 and 1998, Remington technicians were busy developing two new .30 caliber cartridges on the .404 Jeffery case — one to be called the .300 Ultra Mag that would pretty much duplicate the performance of the .30-378 Weatherby Magnum. In those days, short magnums were a hot topic in hunting camps across America, so Remington technicians shortened that case by 0.735 inch and came up with the .300 Short Action Ultra Mag.


From left: .300 Ruger Compact Magnum, .300 Remington Short Action Ultra Mag and .300 Winchester Short Magnum. The Remington offering has faded from the scene, and the jury's still out on the Ruger, but the Winchester has proven popular among big game hunters.

The game plan called for introducing both cartridges during 1999, but someone decided to delay introduction of the .300 SAUM for about a year. Bad mistake. The delay enabled Winchester to beat Remington to the punch by introducing its .300 WSM, and everyone knows that timing is just about everything when it comes to the success or failure of a new cartridge. The .300 WSM took off like a flash and went on to enjoy some popularity among big game hunters while the .300 SAUM fell on its nose with a loud thud at the starting gate.


Sad to say, Remington's short magnum never regained its footing and died an early death. One has only to check out the chamberings offered in the company's rifles to see how true this is. According to the 2010 Remington catalog, not a single variation of the Model 700 in production is available in .300 SAUM while four are offered in .300 WSM. The newest kid on the short-magnum block is the .300 Ruger Compact Magnum or RCM for short. Probably mindful of the fate of the .300 SAUM, the developers at Hornady came up with a way to make it stand apart from its competition.

The Remington and Winchester cartridges come close to duplicating the performance of the .300 Winchester Magnum, but they need a 24-inch barrel in order to do so. By using special propellants, Hornady technicians found a way to virtually match the bullet speeds of the .300 WSM in the 20-inch barrel of Ruger's new Model 77 Compact Magnum.


Whether or not that alone will keep the cartridge alive remains to be seen, but I will say this. While a snub-nosed rifle chambered for a magnum cartridge is nice for the shooter who wants one, not everyone does, and for that reason I think Ruger would be wise to eventually also offer the .300 RCM in a rifle with a 24-inch barrel. According to Hornady, the longer barrel increases factory load velocity by about 100 fps beyond the .300 WSM in a barrel of the same length.


The Hornady cartridge is basically a shortened and necked-down version of the .375 Ruger case whereas the Winchester and Remington cartridges are on the .404 Jeffrey case. The .300 SAUM case is a bit shorter while the .300 RCM and .300 WSM cases are the same length. The latter is a bit larger in diameter, so it's a tad more capacious. According to my measurements, gross capacity of the .300 WSM is 8 percent greater than that of the .300 RCM and 9 percent greater than the .300 SAUM.

To illustrate how the three cartridges compare in performance when handloaded to the same chamber pressure and fired in 24-inch barrels, I have included a comparison table made up of the fastest maximum loads shown for each in the 2010 edition of Hodgdon's Annual Manual.

As you can see, the .300 WSM has a noticeable velocity edge when the three cartridges are loaded with 150- and 165-grain bullets, but when loaded with heavier bullets, their performance is quite close — not great enough to matter in the field.

Even though the .300 SAUM is on its last legs, those who own rifles for it and shoot factory ammo should not be concerned since Remington is not likely to discontinue loading it in the foreseeable future. It is too early to tell how the .300 RCM will fare, but Hornady will surely load the ammunition for many years to come, and I wouldn't be surprised to see Federal eventually hop aboard that wagon.

WARNING: The loads shown here are safe only in the guns for which they were developed. Neither the author nor InterMedia Outdoors assumes any liability for accidents or injury resulting from the use or misuse of this data. Shooting reloads may void any warranty on your firearm.

The .300 WSM offers the advantage of ammunition available not only from Winchester but Remington and Federal as well, and for that reason it is available in a broader selection of bullet types.

The three cartridges are excellent candidates for handloading. In the unlikely event that Remington does someday drop the .300 SAUM, its case is easily formed from .300 WSM brass. Regardless of the cartridge, a quick-expanding 150-grain bullet is the proper deer medicine for open country hunting while a stout 180-grain bullet would not be a bad choice for the biggest of North American game.

That leaves 165 grains as what I consider to be the ideal compromise. The best all-around combination for either cartridge may just be a 165-grain bullet such as the Swift Scirocco, Hornady SST, Sierra GameKing or Nosler Ballistic Tip for deer-size game and the Swift A-Frame, Nosler Partition, Hornady GMX or Barnes TSX of the same weight for bigger stuff such as moose and elk.

As powders go, those of medium- slow burn rate such as H4350, IMR- 4350, H414, W760, Reloder 19, Vihtavouri N150 and Ramshot Hunter are tough to beat in either cartridge.

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