The 300 WSM

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The pros and cons to the short and fat powder column

With gun sales flat at the dawn of the new century, the industry needed a shot of pizzazz – a new cartridge, one with the magical ability to suspend the laws of physics or, failing that, at least inflame the buying public’s interest.

In 2001, Winchester introduced the 300 Winchester Short Magnum, or 300 WSM. The 300 WSM cartridge is based on the .404 Jeffery cartridge, which is shortened to fit a short rifle action.

The WSM introduced the short, fat powder column theory to the shooting public. Benefits claimed to be a result of a short powder column are many: more accuracy, faster powder burn, higher velocity, reduced recoil, whiter teeth and a bigger tax return are but a few. There might be a sliver of demonstrable truth to the faster powder burn, but just about everything else is largely marketing hype or making a lot out of a little.

The .300 Winchester Short Magnum case is 2.1 inches, or 53.34 millimetres, long and only slightly longer than the 308 Win at 2.015 inches, or 51.81 millimetres. The rebated rim case fits perfectly in short rifle actions, as compared to its predecessor, the 300 WM, which requires a long action.

The reworked Jeffery cartridge does not have a belt, as is commonly found on most cartridges carrying the “magnum” moniker. The theory is the short and fat powder column produces a more uniform and consistent ignition because more of the powder is close to the primer’s flash when it’s ignited. This improved and uniform ignition of the powder was the basis of much of the marketing that was wrapped around the new cartridge. Uniform ignition does improve accuracy, but the jury is still out as whether short powder columns are measurably more accurate than long powder columns in the field. The fact that the 300 WSM resides in a short action, which is stiffer and therefore usually more accurate, probably has as much, or more, to do with the accuracy claims as the short powder column.

Other claims were higher velocity and less recoil. In the 150 to 165-grain weight bullets, the 300 WSM pretty much mimics the old standard 300 WM. In most loads, the 300 WSM is almost as fast – the difference is usually less than 50 feet per second. Once the step up to 180 and 200-grain bullets is made, the larger capacity 300 WM over shadows the WSM. As with most things in life, there are no magic potions and the simple fact is more powder capacity means more velocity. Short and fat or long and skinny powder columns be danged.

The WSM profits from new powder technology. Customized powder blends do push the 150 and 165-grain bullets to 300 WM velocities with five or six grains less powder. We know from Sir Isaac Newton that recoil falls under his laws and powder weight is figured into the recoil equation. So, the 300 WSM does recoil less than the 300 WM launching the same 150-grain bullet at the same velocity. The difference is one foot-pound of energy less of felt recoil: 22.5-foot-pounds energy of recoil in the 300 WSM as compared to 23.5-foot-pounds of energy in the 300 WM. There is more than a little skepticism that this difference is noticeable for any shooter.

In reality, the 300 WSM is a repackaged .300 Winchester Magnum, but in a short action. The fat case is not without its problems. The large case head diameter and the very little taper to the case sidewalls results in relatively high bolt thrust levels exerted on the locking mechanism of the rifle action. This can cause difficult bolt lift in some rifle makes and the increased pressures have limited the universal adoption of the cartridge into existing rifle models. This, coupled with the magazine feeding problems that many models suffered in the early years of production, has led to most manufacturers designing a robust magnum short action for the cartridge.

Aside from many of its early challenges, the 300 WSM is a great hunting cartridge for all North American wild game. Flat shooting and accurate, the cartridge lands performance wise somewhere in between the 30/06 and 300 Win Mag.

Pictured: There are a multitude of bullet choices for 30 cartridges. These pictured here range from the 130 grain at the left to the 210 grain on the right side of the picture. This is a very small sample of what is available.

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