One Shot Sight In

Well not exactly one shot - I'm not that good a shooter! But you can zero in pretty well in about 6-8 shots every time. Here is how:
Assuming your rifle is hitting on paper at 100 yards,
1) using a rest fire a three shot group
2) use a gun clamp or a lead sled if you have one, or cut out slots in the top of a cardboard box for the stock and forearm of your rifle.
3)with the gun supported by the box or clamp move it untill the cross hairs are on the center of the target. Make sure it is steady and the gun won't move when you change the scope settings. It helps if using the box method that you have someone help hold the gun steady.
3) keeping the rifle steady, use the dial on the scope to move the cross hairs so they are centered on your three shot group. (reminder - the gun doesn't move during this process, only the cross hairs in the scope)
4) Refire a 3 shot group holding center- if you did this correctly you should be dead on. You may have to put a click or two on to fine tune and then shoot a few confirming shots.
Now with some dry fire practice at home and some time on the gong range using hunting positions you should be ready for that clean, one shot kill!
Good luck!