My main varmint calibers over the years were 222, 308, and 50BMG...depending on range of engagement and number of varmints needed to be dispatched...and .17 Rem, 220 Swift, and 25-06 for coyotes. But nothing with my 6.5 Creedmoors but targets...but I've tested the 6 Dasher 7.5 twist set up for heavy bullets with 55 gr at 4000 fps, 58 gr at 4100 fps, and 70 gr 3700 fps..with fine varmint accuracy...or go semi long with the 110 gr SMK at 3085 fps..
But it doesn't have the dust signature of the 50BMG.