Handloading The .300 WSM

posted on October 17, 2012


The .300 Winchester Short Magnum (WSM) was introduced in 2001 and has become an extremely popular magnum cartridge because big-game hunters and handloaders have discovered it works well with a variety of propellants and bullets to provide good accuracy and high velocity for the amount of propellant burned. Through those years, too, new propellants have been introduced specifically for short magnum cartridges, making the .300 WSM even better.

In working up loads for the .300 WSM I used a Remington Model 700 CDL-SF, which weighed an even 8 pounds with a Leupold VX-3 4.5-14X 40 mm scope mounted in two-piece steel bases and rings.

The recoil from such a lightweight .300 WSM won’t unravel the double knot in your boot laces, plus the SuperCell recoil pad on the Remington soaks up quite a bit of the .300’s kick. But, after more than a few shots, the fatigue from 70-some grains of propellant does tend to accumulate, which makes practice less than perfect.

The .300 WSM adapts well to reduced-velocity loads. A check of handloading manuals shows the .300 WSM burns only three to four additional grains of propellant to duplicate the velocity of the 30-’06 Sprg. Copying the .308 Win. or slowing even further to a .30-30 Win. level requires switching to relatively fast-burning propellants. Using 58 grains of W760 in the .300 WSM propels 150-grain bullets to 2,800 fps to imitate the .308 Win. The same bullet weight at 2,400 fps, from 33 grains of SR4759, turns the .300 WSM into a pleasant approximation of the .30-30 Win. Those reduced-propellant charges soften recoil a third and two-thirds compared to the .300 WSM shooting 150-grain bullets at full-power.

Decreasing bullet weight further dampens recoil. Through the years I have had good luck loading practice cartridges for the .300 WSM with Accurate 5744, H4198, H4895 and Varget and various 125-grain bullets with H4895 being a favorite. One reason is the Hodgdon Powder website has a comprehensive list of reduced H4895 loads for various rifle cartridges that can be adjusted up or down to achieve the best accuracy and desired velocity.

The extreme spread of velocity was 150 fps over 10 shots with H4895 and the Nosler 125-grain Ballistic Tip listed in the load table. That’s most likely because the propellant charge sloshes around like a sea wave to settle any which way in the .300 case. But five-shot groups were round with no vertical stringing. The bullets hit about 3 inches lower at 100 yards compared to 150-grain bullets traveling 3,270 fps. A few clicks of reticle adjustment will offset that.

For hunting, the .300 WSM can be loaded with bullets weighing from 130 grains to 200 grains. The cartridge’s short case and neck (which is still longer than the .300 Win. Mag.) means that bullets weighing 180 and 200 grains will protrude into the usable propellant space. But the .300 WSM case is spacious enough to hold more than 70 grains of propellant with the base of a bullet seated below the case neck. The Nosler 180-grain AccuBond is fairly long at 1.38 inches with its tapered polymer tip and boattail. Yet only about 0.2 inches of the bullet’s base lies below the bottom of the case shoulder with a cartridge overall length (C.O.L.) of 2.85 inches. To make that length cartridge, the Nosler bullet compressed 66.5 grains of Accurate 4350, but only slightly, with no leaning on the loading press handle like a pry bar. Propellant held firmly in place in that manner burns evenly. So what was once considered a ballistic sin is actually a virtue.

Several new propellants have upped the .300 WSM’s velocity. But don’t despair if they’re not on your loading room shelf because many customary propellants provide good speed and accuracy.

Superformance provided the fastest velocity with 150-grain bullets, and Reloder 17 garners top speeds with 165- and 180-grain bullets. Hodgdon lists a velocity of 3,410 fps with 150-grain bullets and 74 grains of Superformance. The Model 700 rifle came up a bit short of that speed, but still faster than any other propellant I’ve tried in the short magnum. Reloder 17 gave the highest velocity to 165-grain bullets at 3,200 fps and 2,990 and 3,040 fps to 180-grain bullets.

Others options are close on the heels of those velocities. They include Reloder 19, Big Game and Hunter with 150s and Supreme 780, Reloder 22 and IMR-4831 with 180s. A lot of old guys who load 4350 propellant started handloading as young fellows using 4350. This standard propellant for decades has been available in slightly different versions from Accurate, IMR and Hodgdon, and it is one of the best all-around powders for the .300 WSM. It provides high speed and excellent accuracy with 125- to 180-grain bullets in the .300 WSM. In the Model 700, Accurate’s 4350 turned in an extreme spread of velocity of 32 fps over 10 shots with Nosler 180-grain AccuBonds.

Western Powders ballistician Keith Anderson said the .300 WSM is an extremely popular cartridge if the amount of calls he receives about loading the .300 with Ramshot and Accurate powders is any indication. The .300 WSM is “inherently accurate and relatively easy to get an accurate load for,” he said, “similar to loading for a .308 Winchester.”

With the .300 WSM’s loading ease, new propellants and the extensive range of weights and styles of .30-cal. bullets available for it, the .300 WSM is destined to become an even more popular magnum cartridge in the next decade.


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