Due to variations in manufacture and the intervention of
humans... anything can happen at least once.
If a similar test was being conducted for purposes of quality control in an industrial setting, then the test sample lot would be at least
30, and the highest and lowest number might be thrown out.
So when you have a sample lot of 2, you can't let anything surprise or upset you. You are trying to draw conclusions and assign faults where it
absolutely cannot be done. All you can do is promise yourself >next time< to be more careful in your loading practices. And this is to say there may have been ZERO errors in your loading practices last time, so this is
not "finger pointing".
If you have deep questions that simply won't stop bothering you, then the only thing you can do is do the test over again, but this time with a much greater sample lot size of 8 to 10.
BRASSTwo words of caution about your samples. Your brass cases will contribute a very large variation in results...
• So use one single brand of brass for all your test samples.
• This is easier said than done, because your 2 most common brands are likely Winchester and Federal. But these guys buy different batches from various vendors. There is "WIN" brass and there is "Win" brass, and they are not the same. There is "FED" brass and there is "-FED-" brass, and they are not the same.
CHRONOThe chronograph remains one of the large variation inputs due to changes in light and inconsistent user technique. Any trees near your range that block light by swaying in the wind can change your readings. If the sun is not straight over-head, then you may need to tilt your chrono toward the sun. New chrono users usually get whacky results because it's simply
not as easy as point-aim-click. Just like music, you have to learn your instrument.
To rule out variations at the chrono, you might load another test set of 8-10 using
jacketed bullets. If their data stacks up nicely, but the HHP do not, then you have valid chrono data that supports your original assumptions.
BULLETSYou've wondered aloud about the differences in bullets leading to the variations you're seeing.
That is a valid concern. But only after
all other components are identical. Make a new sample lot of 8-10 cartridges and
randomly pick bullets out of the Berry container as if you were loading 500.
Loaded this way, if you still see wild variations then you
may need to choose another brand of bullet.
Complicated, YES. Lots of work, YES. But this is the way I would proceed.
