Wow! I discovered the problem! You won't believe it!
You may recall, in my last thread that I tried some CCI 400 primers and not only were the ESs high, 3 primers didn't fire at all. OK, bad batch of primers, or something.
So this morning I loaded up 35 with Remington 7-1/2 primers. Shot 20 of them in my AR, got high ESs and two more primers that didn't fire. Went back in the afternoon and shot the last 15 in a bolt gun. Got one ES of 102 fps and one 114 fps and three primers didn't fire at all. All primers had good hits on them???
So, I'm loading more this afternoon, this time with my old standby A2520 and Federal GM205M primers. I was happily resizing and decapping when something caught my eye - was that a bubble??? I check the primer pocket - it had moisture in it??? I checked 4 others, they too had moisture in them. Somehow they hadn't dried from the ultrasonic cleaning bath! No wonder the numbers were all over the place and primers weren't firing.
I really can't imagine how this happened. I dried them as I always do and this is the first time I've seen moisture. Hmmm, what if other cases had less moisture! It may not have dampened the primer, but may have altered the burn rate of the powder. That would sure explain some things! :yup: