4/19/2021 0 Comments 300 Wsm Reloading Loads
If I could do it over, I would spend more time with 200-grain loads.He sets forth a compact rifle cartridge case design that he describes as shortfat and intended for short-throw bolt-action rifles.The patent details ranges of dimensions and ratios between them that cooperate to generate excellent velocities by shortening the pressures time to peak and by burning more of the propellant inside the case rather than in the bore.
Quite a few cartridges now fall under this design concept, but the one that saw a meteoric rise in consumer acceptance was the.300 Winchester Short Magnum (WSM). Ive spun enough ink regarding my reloading concerns with belted cases that dont need a belt, so Ill not repeat myself here. Suffice it to say, the.300 WSM was already one-up on my scorecard before we squeezed the first trigger. A lot of verbiage has described the Short Magnums as based on the.404 Jeffery case, but the better description is that they were inspired by the old British workhorse. The.404 Jeffery, at 0.545 inch, is smaller ahead of the rim than either Winchester or Remington shortfat designs; they are 0.555 inch and 0.550 inch respectively. My Speer development team was keen to jump into learning about a new cartridge from the ground up. However, we were under pressure to get data out and had to temper our enthusiasmsome things we learned came later. To get data online quickly, we focused on the most popular hunting bullet weights. ![]() The extreme variation (or EVthe highest value in one data set subtracted from the lowest) for the lower charge weight pressures was usually conspicuously higher than those of charge weights closer to maximum pressure. Most tallskinny.30-caliber cases from the.30-06 up show this. It was so pervasive that we called it normal and even adjusted start charge recommendations to avoid these pressure regimes if needed. Immediately, we saw this low-pressure variation was consistently minimal in the.300 WSM. It was seldom greater than EVs of any higher charge weight and definitely averaged less than other.30-caliber magnums. Incidentally, we saw this same behavior in the.300 Remington Short Action Ultra Magnum that also falls within Jamisons patent parameters. If efficiency is getting the most output from the least input, Jamisons concept seems to be working. Before I retired I analyzed the.30 calibers from the.30-06 though the.30-378 Weatherby. I selected lab data using the Speer 180-grain Hot-Cor Spitzer SP and looked for loads producing the highest velocity in a 24-inch SAAMI test barrel and how much propellant it required to reach said velocity. 300 Wsm Reloading Loads Manual 14 InWe used the propellants available to us prior to the release of the Speer Reloading Manual 14 in 2007. I referenced everything back to.30-06 velocities and charge weights, looking for what percent increase in propellant charge gave what percent increase in velocity over.30-06 velocities. The results were interesting, and in some cases they were eye-opening. Setting the.30-06 as a baseline, the well-established.300 Winchester Magnum uses 37 percent more propellant than the.30-06 to attain a 13 percent increase in velocity. Thats no bargain. On the other hand, the.300 WSM uses only 14 percent more fuel than the.30-06 to get an 11 percent velocity gain, a reasonable return. The WSM also posted a maximum average velocity only 49 fps less than its bigger, older brother using 14 grains less propellant. Normally, developing loads for the.30-caliber magnums with varmint-weight bullets was a painful slog through inconsistencies, but the.300 WSM was very well behaved with 110- and 130-grain bullets. We also developed reduced-recoil loads using Accurate 5744 that were very consistent. One of the 150-grain loads roughly duplicated.30-30 velocities with superb consistency in pressure and velocity. You can train new shooters with that load, and as they grow in stature and experience, increase the recoil incrementally.
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