I have sighted in scores of scopes. I put the rifle in a solid rest; line up the barrel on some distant object and then adjust the scope so the cross hairs are on the same object. I do this by centering the barrel on the object and then turning the knobs in the opposite direction they call for. If the scope is too low, I move it lower until the cross hairs are right on the target. After I get the scope and barrel lined up I shoot at 25 yards and adjust as needed. I then move back to 50 or 100 yards and adjust again. I am now zeroed. I use a chronograph while doing this to test loads and do a cleaning regiment on a new barrel while zeroing, to make the most of ammo. If it is a gun I can not look down the barrel like a lever action or auto, I set up at 25 yards and start firing. I take a good sized paper and shoot to the center. If my bullets hit the paper, I adjust accordingly. If they do not hit paper, I start aiming off the paper. I go 6" to the right off the paper, of center, then 6" low, then 6" left and so on until I hit paper; one shot at a time. If I still do not hit paper I move out to 12". It sounds like I waste a lot of ammo, but it really does not take that much. I just shoot one round at a time until I get it close, then start shooting 3 shot groups to finalize the zero. Once I think I got it, then I start shooting 5 shot groups. If I was shooting a rifle that takes $3 ammo, I would probably pay a shop to bore sight it for me, but I do not shoot any thing that expensive. I have used the above described method for years and have never wanted for any thing else. I suppose I would really like one if I got it. I got by with out a chronograph for years and never missed it. Now I have one and would not load develop with it. I think if I got one, I would get the type that has the proper pins for your bore and a grid above the bore to set the scope with. I am sure there will be others along that have more experience with them than I do, I just never felt the need. Good Luck and Good Shooting