What’s the deal with short magnums?

by Bruce Ranta | November 5, 2021
bullets
300 WSM (left) and .300 Win Mag. The .300 WSM has very comparable ballistics to its much longer counterpart. I find the recoil of the .300 WSM to be considerably less than that of the .300 Win Mag.

Magnum cartridges are simply big cartridges with more powder. Bullets are often the same that are used with regular brass. Hunters like magnums for their extra knock-down, killing power. Short magnums have similar power to their standard magnum counterpart, but in a larger diameter, shorter cartridge.

Short magnum rounds are fired in short-action rifles specific to the calibre. A short-action rifle has a shorter receiver and about a half-inch less of bolt travel compared to its long-action sibling.

Development

As far as I can tell, the first commercial short magnum was introduced in 1965: the .350 Remington Magnum. It was based on a 2½ inch, 7 mm belted Remington Magnum case, shortened to 2.171 inches and necked up to .358 calibre. The 1966 Remington introduced the 6.5 mm Remington Magnum. Both were designed to work through the .308 Winchester action. Neither saw much success.

Most credit the current crop of short magnums to benchrest competition shooters in the 1970s. Benchrest shooters tend to be experimenters, are often gunsmiths, typically use custom-made rifles, and handload their ammunition. They discovered that if you necked down a M43 Russian military case to either .224 or 6 mm, gave the shoulder a sharp 30 degree angle, outstanding accuracy, with little loss of velocity, could be achieved.

They found a short, fat case — shortfat — gave improved accuracy because powder burnt more uniformly, which improved charge consistency.

Short, fat, magnum cartridges, did not show up until 1997, when the 7.82 Lazzeroni Patriot was introduced by the Lazzeroni Arms Company. Winchester followed suit, producing the Winchester short magnum (WSM) line. Remington trailed with their short action ultra mag (SAUM). A few years later, Winchester came up with the super-short magnums (WSSM).

Pros

a man retrieves his harvest on snow-smeared slopes
Short magnums are a solid choice when hunting big
game on rugged terrain and where shooting distances
can be great. Premium loads in my . 300 WSM provide
extremely flat shooting out to 300+ metres.

The weight saving of a short-mag rifle compared to the long-mag version is a definite plus. A short-mag rifle can weigh at least a quarter pound less, which is a significant and tangible benefit when hunting in rugged terrain, or whenever you need to walk and tote guns and gear long distances.

Some claim rifles with a short action are faster to reload . On a bolt-action, one might save a couple of tenths of a second to eject a shot shell and reload a fresh round, which doesn’t sound like much and really isn’t. Still, in a hunting situation, every second — or tenth of a second — counts.

The time saving may not be as critical as the overall shorter action. The longer the bolt throw, the greater the chance of catching clothing or debris, or simply not drawing the bolt back far enough to eject the spent brass before trying to seat another. In other words, a short-action rifle should see a lesser chance of jamming.

However, short mags can and do jam. Many attribute short mag jamming problems to having a case diameter larger than the rim, which means the face of the bolt has only a small amount of overlap with the rim of the case, so grip isn’t as good as it could be. When coupled with the sharp shoulder and a rush to reload, jams can occur. But no firearm is immune to jamming.

Short mags’ ballistics are equal to, or slightly better, than regular magnums. But, there are fewer choices in bullets and cartridges, and less availability. Most ammo is premium quality, but expensive.

two firearms laid on a pelt
The much shorter action of a short mag, seen on the bottom, as compared to a long-action caliber.

Short mags use about 10% less powder than a regular mag. Coupled with the powder burning characteristics the end result is reduced recoil. However, being magnums, recoil is still substantial.

Are short mags, like their predecessor the shortfats, noted for great accuracy? Indeed, they are inherently accurate; but today, all premium store-bought ammunition, regardless of calibre, can provide outstanding precision shooting. I don’t reload, but friends and acquaintances that do say there are no issues with short magnums. I’ve shot their reloads without incident.

Cons

Magnum caibres may not have the lasting power of regular caliber firearms. High pressure cartridges can result in premature wear of the bore. My hunting partner Deryk calls my .300 WSM the “fattie” because of the shell shape. In some rifles this means less magazine carrying capacity

Due to the theoretical increased probability of a jam in a panicky situation, short mag rifles are generally not recommended for hunting dangerous game. The knock-down, killing power of a magnum might not always be an advantage. In some typical Ontario hunting situations, magnums, including short mags, can actually be disadvantageous.

At close quarters, magnum loads can whistle through an animal without expanding, especially if large muscle mass or bone isn’t hit. I’ve had this hap-pen twice with whitetails shot with my .300 WSM. One ran more than 300 yards before bleeding out. No firearm or cartridge can do everything. But for many, a short magnum is a very fine firearm to have and use. I like mine, a lot.

Bruce Ranta

Bruce Ranta is a retired wildlife biologist, outdoor writer and photographer based in Kenora. Reach Bruce at mail@oodmag.com

Originally published in the Fall 2020 edition of Ontario OUT of DOORS Magazine

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Comments

  1. Steve Clark wrote: Ive hunted with a .300 WSM fir 10 years and have to say it is the best gun I have ever used. I have shot numerous moose, deer and bear using a 180gr nosler and have found the bullet has performed well on all animals. Due to my shorter stature, I find the overall length of my Browning X-Bolt in .300 WSM much more manageable than its .300 WinMag counterpart!