Last season I used a Mark 4 Leup on my MPR which worked great for me, I didn't find much in the way of error. However over the winter I changed to a Pro target, so decided to have a play with scope configurations - I tried my trusted Mark 4 M1 -10x40 LR/T, another Mark 4 4 -12 x40 FFP and the EB sniper. All mildot rets, same tube size, same mounts etc and what i found was a vast difference in aimpoints at set ranges - each scope gave different secondary zero's 1 = 14yds 1=17yds 1 = 19yds. This in turn played havoc with aim points from 19yds down to 8 yds albeit marginal enough to get the brain working overtime
. So I ended up going for the scope that had easier aim points to remember - this was the EB Sniper.
I now believe that some scopes work better with different guns - the MPR works well with the Leup but not the EB and vice versa with the Pro Target! So try a few