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The Right Amount Of Powder
Today, we’re going to take our quest for the most accurate
load to a new step; finding the right amount of powder to use in your load. Using
"exactly" the right amount of powder is one of the most important factors
in a load’s consistency and accuracy. Before deciding how much powder to use, it’s
always a good idea to research several different reloading manuals and other
load data for the caliber your looking to reload. I first select what
"appears" to be the best powder for the bullet I'm shooting. You'll see what is considered to be a safe
maximum load listed for the particular rifle being tested. Keep in mind that each barrel is unique, and
it will develop a different amount of chamber pressure compared to other
rifles.
Measuring
Velocity
I use a chronograph to measure the exact velocity of my
handloads. The first thing I do is assemble and fire a single round that is
well below the maximum published load. I examine the fired case for pressure
signs, then I usually test rounds that are slightly hotter. Each round is
usually with an extra .3 to .5 grain more powder. After each firing, I'll
examine the primer for signs of excessive pressure. When the edge of the
primers become completely flat, it's time to stop increasing the powder charge,
because that indicates the maximum safe load.
At this point, I shoot the first (5) shot group with my
maximum load. I then make 5 more rounds, and reduce the powder by .3 grains,
and shoot another 5 shot group. I repeat this process a few times while comparing
the accuracy of several lighter loads. Somewhere in this process, I'll find the
velocity range that delivers the best accuracy with my particular rifle and
bullet combination. This method works very well for me.
Don't jump to conclusions after shooting one great group.
Back it up by firing at least two more groups.
It's pretty rare for a shooter to just take a wild guess at how much
powder to use and discover great handloads that shoot well in all rifles. When
you're sure that you've found the most accurate load, be sure to record that
velocity.
Developing handloads with a chronograph is a definite
advantage. With this method you can test any other type of powder by
duplicating this same velocity. You'll almost always shoot the tightest groups
at (or very near) this speed. After you decide on the best powder, you'll need
to experiment with bullet seating depth to see which setting delivers the best
accuracy.
Powder Measure
Here are a few other thoughts on the subject. A chronograph will show how little velocity
is affected by a slight variation in powder charge. After you've decided on an
accurate load, there's rarely a need to weigh individual powder charges. A good
quality powder measure can drop consistent powder charges with most types of powder.
I reload for about a dozen different calibers, and I've only found one caliber
that requires powder charges to be individually weighed for each and every
round. That caliber is the 300 Whisper. Mine needs to have an extremely uniform
velocity, because even the slightest variation in velocity will have a major
effect on its trajectory.
Back when I was shooting in snow country, I once discovered
a surprising amount of unburned powder lying on the snow, in front of where I
was shooting. This shows that it's possible to burn too little of a slow
burning powder, before you run out of barrel length. It's also important to use
magnum primers with the cases that have a huge capacity. Speaking about primers,
if your primer pockets loosen up, it almost always indicates that you're
handloads are generating too much chamber pressure. Try using a different
powder or just back your load down a bit.
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