Brian, maybe battery is the wrong term. I'm speaking from input I got from one of my first posts on this site (http://thefiringline.com/forums/showthread.php?t=491198
) where half of my first run had soft and off center strikes.
Using the feedback from that post and beginning to use the plunk test, I was able to dial in my gear. Clearly have a little bit more work to do to tighten up my quality control because this particular round shouldn't have passed the plunk test.