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American Rifle
Rifle Magazine
December - January 2000
Volume 35, Number 6
ISSN: 0017-7393
Number 208
On the cover...
This issue is only available on CD-ROM.The Winchester Model 70 and Browning A-Bolt are chambered for the new .300 WSM. Purchase the CD-ROM here
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It was bound to happen sooner or later. The new kid on the block is the .300 Winchester Short Magnum (WSM). It’s the newest design in an effort to cram more power in lighter short-action, bolt-action sporters. Developed in partnership with USRAC (Winchester and Browning rifles), Winchester Ammunition’s .300 WSM is a short, fat non-belted cartridge that delivers performance similar to the highly regarded .300 Winchester Magnum.

As we go to press, the Winchester Model 70 will feature a 24-inch barrel and weigh 7 pounds, 4 ounces. You can choose from three variations: the Classic Featherweight, Classic Stainless and Classic Laminated.

On the Browning side, the A-Bolt .300 WSM weighs in at 6 pounds, 9 ounces with a 23-inch barrel. There are four basic models, including the Hunter, Stainless Stalker, Composite Stalker and Medallion.

With an overall loaded length of 2.76 inches the short, fat .300 WSM will arrive on the market with three Winchester factory loads: a Supreme 180-grain Fail Safe, Supreme 150-grain Ballistic Silvertip and Super-X 180-grain Power-Point. Velocity of the Fail Safe load is 2,970 fps with a muzzle energy of 3,526 foot-pounds (ft-lbs). The 150-grain Ballistic Silvertip is stepping out at 3,300 fps and 3,628 ft-lbs of muzzle energy. The 180-grain Power-Point generally duplicates the 180-grain Fail Safe load.

For field application, Winchester Ammunition is rating the 180-grain loads for larger species such as moose, caribou, elk, bear and larger deer. The 150-grain Silvertip is recommended for antelope and deer-sized game. Performance tables show the .300 WSM essentially duplicates the .300 Winchester Magnum and slightly exceeds the .300 H&H.

Winchester provided trajectory information out to 500 yards with a 200-yard zero, indicating about 7 inches of drop below line of sight at 300 yards for the 180-grain loads and around 5.5 inches of drop at the same range for the 150-grain entry. Given the long-range mindset of most modern-day hunters, I suspect a 250- to 275-yard zero might be more useful, assuming relatively open country, but I wouldn’t go over a 2.5-inch midrange trajectory, which puts the bullet about 2 inches high at 100 yards. My reasoning is that too many folks simply can’t estimate range well and often end up shooting over the animal’s back when the range is grossly overestimated, as it often is. It is best to “hold on hair” for the first shot. If the temptation to hold daylight over the back is burdensome, then chances are it is too far to shoot anyway.

While Winchester Ammunition states the new WSM cartridge is not based on any existing cartridge design, there is plenty of precedent for short, fat cartridges in recent memory. One of the first was the Gradle Express series that was based on the .348 WCF case with the rim turned down to a rimless design. Case capacity was slightly more for any given caliber than might be available from a wildcatted .404 Jeffery case, for example, that is cut back to 2.1 inches. Of course, there have been a variety of attempts to wildcat the .404 Jeffery case in long, medium and short versions over the years. One of the most popular was known as the G&A line. They were mostly big bores for African game, but they worked.

Presently Jim Busha has a Heavy Express line of wildcats based on a rimless version of the .348 WCF. Lazzeroni also has a short, fat wildcat based on the .416 Rigby case.

In reviewing the history of the short, fat case designs that have cropped up over the years, the time couldn’t have been better to modernize the concept in a standard factory cartridge lineup that could easily be expanded to include 7mm, .338 or .375; take your pick.

The reason I say the time couldn’t be better for a modernized cartridge design is that the short, fat concept simply couldn’t have gotten off the ground a dozen years ago. The reason was bullets. For larger game such as elk or moose, most seasoned hunters wanted heavier .30-caliber bullets that could not be efficiently loaded to 2.76 inches overall length in a short action, like a .308 WCF, for example, and still generate enough steam to take on heavier game. As a result, some of the more efficient short-action cartridges like the .284 WCF and .308 WCF were largely ignored in favor of longer belted cases in standard length actions that could utilize the heavier bullets more efficiently.

While an elk hunter might appreciate the advantages of the 175-grain bullet in the 7mm Magnum, that longer, heavier bullet left the .284 WCF hamstrung in a short action. The same goes for the heavier slugs in the .350 Remington Magnum when restricted to an overall loaded length of 2.7 inches or so.

Nowadays, however, we have premium 150-, 165- and 180-grain .30-caliber bullets that can not only do the work of the heavyweights of yesteryear, but they also can do it even when reined in by the velocity restrictions dictated by short actions - albeit utilizing the short, fat case concept to the fullest extent practical.


As a matter of fact, the quality and overall effectiveness of nearly all big game bullets from a variety of sources has improved so much over the last dozen years that nearly any of them would serve well in the .300 WSM, or a 7mm, .338 or .375 version of the same case concept. That strikes me as why Winchester felt comfortable including the 180-grain Power-Point in the new WSM lineup. Handloaders might think more in terms of the Hornady SST, Barnes X-Bullet, Swift Scirocco, Speer Grand Slam, etc. There is also a   long list of custom bullets from Hawk, DKT, etc. with bonded cores to choose from.

SAAMI drawings for the .300 WSM are not available as we go to press, but we do know the rim diameter is similar to the standard for a belted case design - about .532 inch. The case body, just in front of the extractor groove, averages .555 inch. The shoulder angle is 35 degrees, the same as the .284 WCF. Case length is 2.1 inches and overall loaded length is 2.76 inches. If you know your basic brass dimensions, these numbers describe a .348 WCF necked down to .30 caliber and the rim turned down to .532 inch. That pretty much splits the difference between the .416 Rigby and .404 Jeffery in terms of case body diameter.

The Winchester Ammunition news release said the new cartridge is not based on any existing case design, but it really is a .348 WCF with a slightly rebated rim. For the history nuts, that’s a Gradle Express from the 1950s or a Rimmed Express developed by Wade’s Gun Shop out of Phoenix, Arizona, during the same time frame.

I know some readers are wondering, “Why the short, fat case?”      It started with a couple benchrest shooters back in the early 1970s - Ferris Pindell and Dr. Louis Palmisano. They fiddled around for a few years and came up with a cartridge design based on the .220 Russian. They called it the .22 PPC (Pindell-Palmisano Cartridge). They took the new cartridge to the 1976 Super Shoot and cleaned house; benchrest shooting has not been the same since. The common denominator between the .22 PPC and later benchrest cartridges was the short, fat powder column, which some believed helped to develop more uniform combustion - hence, accuracy.

While the .22 PPC has evolved into the 6mm PPC and a series of Remington benchrest cartridges, the concept never made it into big game sporting rifles, except for a couple lines of proprietary cartridges. For the most part, it seems long belted, or non-belted, cartridges still ruled in the field where accuracy, while certainly desirable, didn’t require putting three to five rounds in one hole out to 200 yards. So sport hunting has never embraced the short, fat concept, at least not to the extent it would support the kind of investment it takes to develop a new cartridge case and subsequent factory loads for a brand new rifle chambering. A key official in the ammunition business once told me it takes nearly 10 years to recoup the investment that is involved in bringing a new cartridge to dealers’ shelves. That’s a long time to wait just to break even on what can amount to nearly $250,000 investment. No wonder the ammunition and rifle manufacturers appear so conservative.

The new .300 WSM pretty much embodies just about all we know about inherent accuracy, effectiveness and efficiency in modern sporting rifles and cartridges. It is, however, somewhat ironic to learn that it is apparently based on a cartridge that Winchester has had in the lineup since 1936. Before that, the basic case was known as the .50-110-300 or .50-100-450, which date back to 1887 and 1895, respectively. Just when we think we have something really new and innovative, we find it’s been around for 113 years!

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