Do you know what its like to put the cross hairs where they’re supposed to be and not have the bullet go there? I do and man it’s extremely frustrating. I was using Sierra I-5 ballistic software some time ago and time and time again I checked to make sure everything was right. I was ok to about 400 yards, but from there on I kept on getting further and further away. I thought to myself, ok my muzzle velocity must not be right, but it was. Then I thought, maybe the atmospheric data was wrong, but it was right too. I even changed my zero to try to make it line up, but that didn’t work either. Even when I broke my flight path into different velocity regions and changed the BC (ballistic coefficient) value in each region, trust me that was a headache, still not even close. You see my scope is 1/8 MOA, which is an 1/8 inch at 100yds, OR so they say. So what I did, is put a target up at 100yds and dialed my scope 40 MOA which should be 40 inches at 100yds. But when I did, I actually only got 26 inches. Now divide 26 inches by the number of clicks it took and that gives you your actual click value, which in this case it turned out to be .0875 instead of .125 (1/8) MOA. Now some ballistic software allows you to change your click value to the correct amount, some don’t. Sierra I-5 does not. So I changed my software to another type and have never had a problem since. Millett, the manufacturer of my scope, the TRS-1, was kind enough to calibrate my scope to the correct amount, another plus.