I've never used a bore sighter and don't bother with shooting at 25 yards or even 50. I go right to 100. My method involves taking the bolt out and sighting down the bore to the target while the rifle is held in a steady rest. I try to center the target in the bore and compare that to where the reticle is situated on the target. I make adjustments to the reticle as needed. This takes just a little while going back and forth looking at the target through the scope and through the bore. When satisfied that I'm close, I shoot a group of 3 shots. This usually puts me within 3 or 4 inches of the target and from there I can make final adjustments to the reticle.