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The Ultimate Reloading Manual
Wolfe Publishing Group
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  • alliant reloading data
  • reloading brass
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The Ultimate Reloading Manual
hornady superperformance

Powder Charges

Author: Richard Mann / Wolfe Publishing Co.
Date: Jan 01 2010

The consistency of the ammunition you load is tied to the consistency in the amount of powder you put into each case. Often, when working up loads, I’ll increase the powder charge about one or two percent at a time, checking the velocity and point of impact as I go. As you near the maximum load it’s not uncommon to find that the point of impact at 100 yards for several, minimally different charge weights will show no variation. This is, of course, rifle dependent.

Even though small differences in powder charge weight can have
no influence on group size at close
range, they can drastically affect trajectory at longer distances.

For example, using Ramshot TAC powder, I worked up some Nosler 150-grain AccuBond, .308 Winchester loads for my sister to take to Africa. At 100 yards the point of impact for cartridges charged with 45.5 grains of powder was identical to those charged with 46.5 grains. However, the muzzle velocity varied almost 100 fps between the 45.5-grain loads and the 46.5-grain loads.

I settled on the 46.5-grain load, but had I been using a stick powder with larger granules, I would have more than likely set my powder measure to throw a 46.0-grain charge. Often, when mechanical powder measures are used to throw charges of hard-to-meter powder like, say, IMR-4895, you can see variations as high as .5 grain. By going with 46 grains, it would not have mattered if the charge came out of the measure .5 grain above or below 46, because point of impact would not have varied – at least at the less than 300 yards distances she intended to shoot.

When shooting at long range, consistent velocity is a bit more important. This is easily illustrated by looking at a .223 Remington loaded with a Nosler 40-grain Ballistic Tip with a velocity variation of 100 fps. This load will drop an additional 4 inches at 500 yards if the bullet leaves the barrel 100 fps slower. Similarly, shoot a Berger 168-grain VLD from a 7mm Remington Magnum at 2,700 fps instead of 2,800 fps, and it will drop almost 10 inches farther at 700 yards. In the first instance, this velocity variation could cause a miss on a prairie dog. In the second example, the difference could mean a miss on a pronghorn.

Manual powder dispensers are commonly used by many handloaders.
They can produce accurate ammunition,but it is dependent
on their ability to consistently throw powder charges with identical weight.

Sometimes you’ll also find that minimal powder charge variations can adversely affect group size. I’ve found this to be especially true with rifles that have pencil-thin barrels. Two lightweight Kimber Model 84 rifles I experimented with, both .257 Roberts, were extremely sensitive to the powder charge. In some instances half a grain of powder would double group size. 

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