I start out at 25 yds, get it on paper if nothing else till you get a group of three. Then move back to 50 yds, do the same, about a inch high, then see where you are at 100 yds. then depending on where you hunt an how long your shots will be go from there. I have my center fire rifles dead on or no more than one inch high at 100 yds. My muzzleloaders either dead on at 100 yds or just under. My longest killing shots todate are 165yds, but most are around 75-100 yds or even less.