Thanks for the replies. Here is a pic comparing Hormady XTP versus the all copper Barnes TAC-XP. On each end is a jacketed lead 155gr XTP. left to right in the middle are the 125gr, 140gr, & 155gr Barnes TAC-XP. I have some Barnes samples in the 140gr and 155gr on the way - we'll see what groups the best.
When I plug my data into the Miller stability chart, the 155gr Barnes seems the best bet for my application.