FWIW you can set your sights dead on @ 50 yards with your most accurate load, the check at 25, 30, 40, and yes, 60 to know the trajectory of your rifles load. From muzzle to 50, 32s are pretty flat shooting. Not all guns will allow this though. Where it is harder to sight well because of distance, shoot squirrels in the lower ribs. It is a humane shot and not very meat damaging either. I carry several bread bags, and clean bagged immediately, and they ride home in the haversack. It is helpful to set up with a sapling or two close enough to use as a rest.
This works well in late season eastern hickory groves where the squirrely rascals maybe foraging on the ground coming to you, or are sitting on a limb watching you and the brush is not thick.
Good Hunting Lon