1. Uniformity - stated very succinctly by stiff neck.
2. Keep good records! I agree with bownut. Record everything, even the environmental conditions when you're testing your loads!
Bottom line, if you do #1 & #2 you should be able to achieve repeatability.
No offense to the other contributors to this thread! I mean, I could say "safety glasses" and it would be hard to disagree with the importance. Fact of the matter is this: if you need someone to tell you to be safe when reloading, then you probably shouldn't reproduce. But, just in case, BE SAFE! You can't do #1 or #2 above if you're blinded by an explosion on your reloading desk!
Good thread. Good luck & God bless.
~Scott
