I always bore sight a gun first and make any major adjustment by shimming or adjusting the mounts. I prefere mounts that have windage adjustments built into them. This way you don't have to fire as many rounds or put as much adjustment into the scope. I have seen people ruin scopes by over adjusting them. And if you take up all your adjustment range for sighting it in you don't have any left for elevation or windage correction if you need it.

After that I fire a few groups at 25 yards and do any fine tuning that might need to be done. Bore sighting does not always get you as close as you think it will, so starting at 100 yards might be futile in some cases. If I am more than a few inches off at 25 yards I will fix it in the mounts again before actually doing any dialing on the scope.

After this I sight in at what ever yardage I want the gun zeroed for. And shoot at least three shots. Don't fire a round and adjust, then fire another and adjust again. Unless you know your gun is very accurate and you know you made a good clean shot. I still don't suggest doing it with one shot. I also might try different loads at this time to see what is more accurate out of my gun if it is new. I don't bother adjusting the scope until I find a load I like because changing loads will change your impact points some times.

I use a target with a 1 or 2 inch square bull. I also only adjust one axis at a time. I start with elevation, then do my windage. After that I fire another group or two or three to see if anything needs touched up. I line the cross hairs up on the horizontal line and only concentrate on keeping the gun steady for elevation. If it wants to float from side to side I let it. I center the group on this line. Then I line the vertical cross hairs up on the vertical side of the bull and concentrate only on keeping the gun steady from side to side and center the group on the verticle line of the traget.

After this I aim for the corner of a square lining the cross hairs up with the corner of the bull and see where my groups land.

This is a very precise way of shooting since it easier for your brain to conentrate on one axis at a time rather than two. And I only adjust one axis at a time because if your scope is not leveled perfectly or you do not hold the rifle perfectly level adjusting both turrets at once might pull your shots to one side or up and down.

I tune my archery equipment the same way.

This is how I was taught to do it by a bench rest shooter and it seems to work very well. It is time consuming and uses more ammo but it is very precise.

Paul