On the jump/velocity questions, I read something about longer jumps giving lower velocity spreads in a fleet of PRS guns. I was working on a 7/300PRC set up for 190s at the time. Those results were:
Jump, Avg Vel, ES, SD
10 Jam, 3025, 11, 4.9
25 Jump, 3002, 10, 4.3
50 Jump, 2999, 14, 5.2
75...