What is the real hunting difference between a lighter ELD-X and a slightly heavier ELD-M bullet at say 400 -500 yards on heavier game like elk? Specifically, my 6.5 CM & PRC will both shoot Hornady factory 143 gr ELD-X & 147 gr ELD-M sub-MOA. I like the idea of greater BC despite slightly slower velocity of the heavier ELD-M.