.300 Winchester Short Magnum

.300 Winchester Short Magnum (also known as .300 WSM) is a thirty caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2001 by Winchester.^[1] The cartridge overall length is 72.64mm, cartridge case is 53.34mm in length and the bullet diameter is .308 in (7.82mm), which is common to all U.S. .30 calibre cartridges. The principle at work in the short magnum cartridge is the advantage of fitting larger volumes of powder in closer proximity to the primer's flash hole, resulting in more uniform, consistent ignition. In field use, this round mirrors the performance of its older counterpart, the .300 Winchester Magnum, which is based on a modified .375 Holland&Holland belted magnum casing.

The big advantage to this round is ballistics that are nearly identical to the .300 Winchester Magnum, but in a lighter rifle, with a shorter action.. Of importance to some rifle shooters is the increase in efficiency of shorter casings, which results in greater inherent accuracy.

When addressing this topic, it is useful to consider the true degree of accuracy involved. This degree is fairly minute for most uses, and is primarily important to target shooters, and hunters who rely on a rifle to be capable of extreme long range accuracy. Very few rifle shooters are able to shoot better than their rifle. The basic issue at hand is that this cartridge is in a class that is already filled with numerous choices in similarly performing rounds, and has little to distinguish it but nominal increase in accuracy, and lighter felt recoil. The .300 WSM is, however, the most modern .30 caliber cartridge in the magnum class, utilizing the best available knowledge in cartridge design. As such it represents the best combination of ballistic performance, round-to-round consistency, and reduced recoil and muzzle blast.

Use & Performance

The .300 WSM is used in the Western United States for elk, mule deer, and whitetail and on the plains, where long range shooting is almost always a must. While being relatively new cartridge, the .300 WSM has already had some success in benchrest shooting, although flatter trajectory rounds such as the 7 mm WSM, .270 WSM, etc., are normally preferred.

As with all high speed large game rounds, bullet construction plays a major role in terminal ballistic performance. If the gun is accurate enough for its intended purpose, what will make or break it is what the bullet does when it strikes its intended target. High velocity—extremely high in this case—cartridges have a set of problems all their own. If a bullet intended to perform perfectly in a lower velocity cartridge of the same caliber (such as .308 Winchester, or .30-06 Springfield) is used in the .300 WSM, the result is fragmentation and a shallow cavity; i.e. essentially a massive surface crater with poor penetration. With the right bullets, the .300 wsm is a devastating round on medium to heavy North American game animals. ^{[2] [3]} The actual bullet diameter used in this cartridge is .308 inches. Care should be taken to avoid using improper ammunition.

Muzzle velocity

• 10.69 g (165 gr) Full Metal Jacket(FMJ): 3,223 ft/s (982 m/s)
• 11.66 g (180 gr) Full Metal Jacket(FMJ): 3,095 ft/s (943 m/s)

Comparison

See also

• .300 Remington Short Action Ultra Magnum
• .300 Winchester Magnum
• Winchester Short Magnum
• List of firearms
• List of rifle cartridges
• List of individual weapons of the U.S. Armed Forces
• 7 mm caliber
• Delta L problem

References

1. ^ The .300 WSM (Winchester Short Magnum) by Chuck Hawks (subscriptions req)
2. ^ Iowa IBS 1000 Yard Match Results - Aug 2006
3. ^ Montana Northwest 1k yard Club Results - Aug 2006
4. ^ .308 Caliber reloading data at Accurate Powder
5. ^ http://www.accuratepowder.com/wp-content/uploads/2011/01/accurate_load_data_3.5.pdf