Why buy a bore sighter. i used one at the shop i worked at but i do this and it works pretty good for me. i remove the bolt from the rifle. place the rifle in my mtm gun cleaning cradle or you could use a vise. i place a piece of paper on the other side of the room and line the bore with a dot or a mark on it .i try and get it in the center of the bore . i then look through the scope without moving the rifle. i adjust the crosshairs to the point on the paper.
i sometimes will find something outside the house and do this .
i then shoot at 50 yards and adjust and move to 100 .

SOUTH ARKANSAS REBEL