by now youve already shot the gun and you may have found out that your gun shot off even though your cross hairs were dead center on the grid marks most boresighters get you on paper and thats it . some of the laser sighters are very reliable and offer a referance card for each gun you have so you can check zero without shooting your gun. i have a BSA borsighter and when my gun is zeroed in at 100 yards by shooting and checking zero my cross hairs are all the way on the right side of the grid and two block grids down in my borsighter. when i first boresighted it in i sighted my cross hairs dead center of the grid up, down,left,right when i shot it at my range i was 3 feet off and low it has somthing to do with the way the guns are drilled and tapped for mounts and the highth of the mounts and rings play a factor in it as well , a good scope has enuff adjustment to take up a lot of the windage(left,right)and yardage(up,down) that it lacks to be zeroed in ,they make scope bushings that take up space to raise or lower a scope or move it left or right without having to move your adjustments on your scope and lose what they call the optical center of your scope .
leupold makes windage adjustable scope bases that lets you keep your optical center of your scope they claim if you keep your scope opticaly centered it is clearer and sharper at longer distance and theres not too much strain on the cross hairs and they stand up to heavier recoil.
well i hope this helps and i hope your gun drives tacks
