I use the same rifle for ground squirrels, rabbits, and coyotes with the same bullet. 223 40gr Vmax ~3700 fps.
For ground squirrels (mostly in the field) I use a 150 yard zero because from 25-175 yards I'm +/- a half inch. Works good for me because sometimes the squirrels are down on all 4, other times all I can see is a head. I need pinpoint accuracy for my "typical" shooting distances.
After 150 yards I prefer to use my rangefinder and Nikon tactical scope knobs along with a ballistic chart from eskimo.com. The chart is taped to my stock. If I don't have time to use the rangefinder on a longer shot, I can just guess it's at say 300 yards and make the scope adjustment real quick.
For coyote hunting I usually leave the scope zero'ed at 150 yards because I rarely get a shot past 200 yards. However, if I'm setting up on a stand with a long field of fire, I can always turn my scope knobs to set it for whatever "zero" I want. Changing from a 150 yard zero to a 250 yard zero is just a matter of a few clicks and then I don't have to worry about holding over at all. It's all in the knobs.
Works for me.
