JBM has a lot of options and a few different calculators, if you really want to get into it. I tried a couple of the others prior to finding it, and really havent looked elsewhere since. I dont really use a lot of what they have, but as long as I get the input as tight as I can, and know my ammo's actual velocities, things seem to jive real close.
Just out of curiosity, how much time do you have shooting iron sights?
Sometimes the target vs practical zeros use can cause some problems, especially where you use a 6 o'clock hold on a target with a few inches from 6 and center, and youre zeroing the gun to center.
If your only target shooting, at known distances and known targets, its not a big deal, and a 6 o'clock hold gives a better, more consistent aiming point. If youre trying to use that zero, and hold right on with those sight settings, youre going to have a different experience I think. Youre either going to be high or low, depending on how you zeroed the gun (6 o'clock vs a dead-on hold).
If youre using a bullseye target, and a 6 o'clock hold, Id zero so the rounds hit at the 6 o'clock aiming point, and not above it in the center.