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.300 Winchester Short Magnum
From left to right: .300 Winchester Magnum, .300 WSM, .308 Winchester, .223 Remington
Type Rifle
Place of origin USA
Production history
Designer Winchester
Manufacturer Winchester
Produced 2001
Bullet diameter .308 in (Bad rounding hereScript error mm)
Neck diameter .344 in (Bad rounding hereScript error mm)
Shoulder diameter .538 in (Bad rounding hereScript error mm)
Base diameter .555 in (Bad rounding hereScript error mm)
Rim diameter .535 in (Bad rounding hereScript error mm)
Case length 2.100 in (Bad rounding hereScript error mm)
Overall length 2.860 in (Bad rounding hereScript error mm)
Rifling twist 1-10"
Primer type Large rifle magnum
Ballistic performance
Bullet weight/type Velocity Energy
150 gr (Bad rounding hereScript error g) SP3,313 ft/s (Bad rounding hereScript error m/s)3,657 ft·lbf (Bad rounding hereScript error J)
165 gr (Bad rounding hereScript error g) HP3,223 ft/s (Bad rounding hereScript error m/s)3,807 ft·lbf (Bad rounding hereScript error J)
180 gr (Bad rounding hereScript error g) HP3,095 ft/s (Bad rounding hereScript error m/s)3,830 ft·lbf (Bad rounding hereScript error J)
200 gr (Bad rounding hereScript error g) SP2,822 ft/s (Bad rounding hereScript error m/s)3,538 ft·lbf (Bad rounding hereScript error J)
Test barrel length: 24"
Source(s): Reloading data at Accurate Powder

.300 Winchester Short Magnum (also known as .300 WSM) is a .30 caliber rebated rim bottlenecked centerfire short magnum cartridge that was introduced in 2001 by Winchester.[1] The cartridge overall length is 72.64 mm, cartridge case is 53.34 mm in length and the bullet diameter is .308 in (7.62 mm), which is common to all U.S. .30 caliber 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 advantage to this round is ballistics that are nearly identical to the .300 Winchester Magnum, but in a lighter rifle with a shorter action. A disadvantage of cartridge case designs with relatively large case head diameters lies in relatively high bolt thrust levels exerted on the locking mechanism of the employed fire arm.

Use and performanceEdit

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 velocityEdit

  • 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)


.300 WSM performance comparisons [4][5]
Cartridge Bullet Weight (gr) Muzzle velocity (ft/s) Muzzle energy (ft·lbf)
.300 WSM 200 2822 3538
.300 RSAUM 200 2790 3458
.300 Win Mag 200 2850 3550
.300 Wby Mag 200 3060 4158
.300 RUM 200 3154 4419
.30-06 Springfield 200 2569 2981

See alsoEdit


  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

External links Edit

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