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300WSM-COTM

Wayne van Zwoll
2610 Highland Drive
Bridgeport WA 98813
File name: NOR300wsm14

.300 Winchester Short Magnum

      You could say the first successful 30-bore cartridge on a short magnum case hailed from Norma of Sweden 55 years ago. The .308 Norma Magnum, based on the .300 H&H, has a 2.56-inch case, slightly longer than the 2.50-inch hulls of .458, .338 and .264 Magnums developed Stateside in the ’50s. Packing .300 H&H performance into cartridges that didn’t require costly Magnum Mauser actions made sense. By the mid-1960s, rifles commonly chambered to the .30-06 were offered in 7mm and .30 belted magnums of the same length. Forty years later, the definition of “short” changed.

     The .300 Winchester Short Magnum appeared in 1999, designed for rifle actions scaled to cycle the .308 Winchester. The .300 WSM offers the ballistic smash of belted .30s in a hull 2.10 inches long. Loaded, the cartridge measures just 2.76 inches – compared to 3.47 inches for the .300 H&H, and 3.30 or so for the .308 Norma and .300 Winchester. The WSM’s .535 rim fits bolt faces machined for the .532 rims of belted magnums. Forward of the web, WSM cases are larger in diameter, so powder capacity is similar. Magazine capacity in boxes fashioned for the .308 is, of course, reduced.

     The notion of driving bullets fast from compact cases dates back not 15 years, but at least 100, to the .250 Savage. Charles Newton developed that fast-stepping .25 for Savage in 1913. The compact .300 Savage that followed in 1920 gave the lever-action Savage 99 more muscle than hunters could get from open-topped Marlins and Winchesters of the day. But powders and bullets couldn’t wring as much from those cartridges as is possible now. The .300 Savage fell well short of matching the .30-06 ballistically, partly because rifle actions (and steels) used then lacked the strength of modern mechanisms.

     Early in 1999 Browning approached Winchester with the idea for the WSM line. Start-up proved turbulent, as entrepreneurs wrangled with companies over patent rights. The .300 WSM got the jump on a similar .30 from Remington: the .300 Short Action Ultra Mag. Winchester followed up with a .270 and a 7mm on the WSM case, later a .325 (8mm). While Remington’s .300 and 7mm SAUM are fine rounds – and just enough shorter than the WSMs to suit its Model Seven rifles – Remington came late to the party. As Winchester launched the .300 WSM, the people at Ilion were promoting their potent new full-length Ultra Mags. By the time Remington announced short rimless magnums, that field was getting crowded, with Hornady poised to release its .300 and .338 Ruger Compact Magnums. At 79 grains, the WSM hulls boast the greatest (water) capacity.

     Chris Hodgdon points out that powders suitable for belted .30s also serve ably in the .300 WSM. H4350, for example. “But the .300 WSM squeezes more energy from each grain than the .300 Winchester Magnum. While 64 grains H4350 in the WSM sends a 180-grain bullet out the muzzle at 2,950 fps, you need 67 grains to get 2,920 from the .300 Winchester.” Norma MRP (Magnum Rifle Powder) is another fine propellant. So too RL-19, Winchester 760, Hybrid 100V, H4831SC and Vihtavuori N550.

     I got my introduction to the .300 WSM in Colorado, when a bull elk eased from the timber. That shot could have been made with a .300 Savage, but the extra reach afforded by the WSM was a comfort. That it’s available in rifles much lighter than the lever guns of a century ago, and cycles with a bolt throw of less than 3 inches – well, those are bonuses. Some shooters claim less recoil from the .300 WSM than from its belted counterparts. I can’t feel a difference, given bullets at equal velocities.

     Norma-USA loads include the .300 WSM with an open-point 155-grain Kalahari, plus 165- and 180-grain Oryx bullets. From deer to elk, moose and big bears, these options make the .300 WSM one of the most versatile .30s anywhere, a worthy heir to the .308 Norma Magnum!

 

Ballistics, .300 WSM, Norma-USA

155 Kalahari        Muzzle        100 yds.    200 yds.    300 yds.    

Velocity, fps        3250        2925        2622        2339
Energy, ft-lbs      3636        2944        2366        1883
Arc, inches          -1.5         +1.3           0           -6.4        

165 Oryx        Muzzle        100 yds.    200 yds.    300 yds.    

Velocity, fps        3190        2895        2619        2359
Energy, ft-lbs      3729        3071        2513        2039
Arc, inches          -1.5        +1.3            0           -6.4

180 Oryx        Muzzle        100 yds.    200 yds.    300 yds.    

Velocity, fps        2960        2696        2447        2211
Energy, ft-lbs      3503        2906        2393        1955
Arc, inches          -1.5        +1.6            0           -8.5

Captions:

1 – The .300 WSM, first and still most popular of WSMs, now features 165- and 180-grain Oryx bullets.
2 – Ballistic kin to the .308 Norma and .300 Winchester Magnums, the .300 WSM is shorter, lacks a belt.

 

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Published on Tuesday, 01 July 2014 00:00