I find it is better to clamp the gun in a fixed position.
Sight in the crosshairs for the distance you are shooting at (elevation)
Then tune in the laser to the crosshairs in the scope.
At the distance you have set it at,the laser dot will be spot on.
A laser beam travels in a straight line,and all pellets and bullets have a lob trajectory,so sighting your scope to the distance you are shooting at is crucial.
i.e--setting the distance at 40yds for instance,the top of the lob/trajectory would be 40yds,this gives you a few feet before and after 40yds where the hit will be still accurate.
Before the few feet,it will shoot low,after the few feet,it will shoot low also.