Monday, September 3, 2012

Little Dandy Powder Measure Test

A good friend, alchemist and all around mad-scientist asked me whether an RCBS Little Dandy Powder Measure might be a good addition to his loading setup.  He has need of some relatively small metered charges of either Winchester 231 or Alliant Bullseye for a loading project he is finishing up.  His powder measure is set up for a different charge and he doesn't want to fiddle with it and he doesn't want to have to weigh every one of the small charges. Since I fell into 4 of the measures and a cigar box of rotors a while back, I offered to help him determine whether they might be accurate enough for his purposes.

The process was simple.  Throw twenty charges of Bullseye from the measure and see whether they were all pretty much the same.  For an electronic scale, I used the scale on my Lyman DPMS II.   Each charge was dropped into the scale's pan, the pan was placed on the scale, the cover closed and then left to sit for a slow count to ten to let anything that needed settling down settle down. The result was then written in a log book and the powder on the scale was put back in the measure before the next charge was thrown.  That way, the amount of powder in the measure was always the same whenever a charge was being thrown.

The smallest rotor I have is a #1.  I have learned that they do make smaller ones. Those are #0 and #00.  The chart for the measure says that the #1 rotor will throw a 2.5 grain charge of Bullseye.  Small enough for test purposes.  One thing about this measure is that, if you want a charge that is between what two adjacent rotors throw you can always buy the bigger one and drop some solder, epoxy or JB Weld into the chamber and then whittle it out once its solidified or cured to get a rotor that will throw what you want.

The first thing that became apparent was that, with my particular lot of Bullseye, the charges were a tad heavier than the chart said they would be.  That's why they say to weigh the charge it throws when you get started to make sure its throwing what you think its throwing.  The second was that there were times when the charges were so close to whatever tolerance the scale uses to decide whether its weighing 2.7 or 2.8 grains that it would often just sit there alternating between the two numbers.  That's why I gave it a count of ten to settle down before taking the official reading.  Still, even with a count of ten, half the charges were so close to the scale's tolerance that they never did decide on which side of the fence that last 1/10 grain should cast its vote.

Here's how it worked out:

Looks like something like 2/10 to 3/10 of a grain variation could reasonably be expected.   That's assuming that the scale is reasonably accurate itself.  0.2 to 0.3 isn't that big a deal unless you are right on the ragged edge of safety.  As a percentage of the charge thrown its pretty big but these are tiny charges so anything is pretty big by comparison.

I did not test  any 231.  By the time I got done with the Bullseye I was so preoccupied with the numbers that I did a stupid thing.  I realized what I had done  before it had a chance to cause any harm but I decided that if I wasn't paying any better attention to safety than I evidently was, (or wasn't) I should get the hell out of the reloading room and do something else.

I will mitigate the stupid thing that I did after dark tonight so it can't hurt anybody.   It will make a pretty post.  

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