I run a DTA and if I switch from 6.5 Creedmoor to 308, my POI shift is something like 0.2 mils in elevation and 0.1 right, but it's repeatable. As long as your shift is repeatable, you can account for it when switching barrels just by dialing to your correction. Any dialing you do from then should be based on your current "zero", meaning if you have to start with your elevation at 0.2 mils because of a POI shift and you need to dial 8.7, you'll end up dialing to 8.9 or you can simply dial in your shift and re-zero the turret