I have a laser bore sighter I used to use/ It is more of an agrivation than useful. Now what I do is dismantle the gun as far as necesary to see down the barrel. On lever actions, you are pretty much screwed, But Bolt actions, AR's, and the like It works great. Just set the gun on sandbags and site in down the barrel on a target of choice, look down the scope carefully without moving the gun and note the adjustment needed to correct the zero. I usually do this at greater than 50 yards. 100 yards is good too.Keep in mind that your barrel will be correct and your scope will actually need to be adjusted to the barrel, so your scope adjustments will read backwards. For example You look down your barrel and see the center of your target , but look through the scope and see that the crosshairs are 8 inches high, you need to adjust the scope "up" 8 inches to get to the scope crosshairs. I have sighted in all sorts of guns like this and all have been on th paper first shot. Laser boresighters are onl;y needed for lever actions and a few semis