The rifle I got has scope mounts as the guy I got the gun from wanted to keep the scope that was on it for his other rifle. fine. So, I bought a new scope and attached it to the mounts. I shot a few rounds at the target 50 yds. and 100 yds. Not even close to the center. With the open sights it's accurate. Looks like I need to bore sight it. what's the best solution for this without needing to fire multiples of rounds of ammo to adjust the scope settings? how often do you bore sight your hunting rifles? what method or preferred type of bore sighting device that isn't going to be expensive?