I use mine to bore sight 5.56 and 7.62 from time to time but never in my air rifle.

I found that the unit is badly made and the laser diode is not central in its positioning which could allow a large circle to be made if you rotated it which would be incredibly misleading.

You could just strip the weapon and boresight it the traditional way by keeping it aimed at an object 100m away and adjust the cross hair onto that point whilst looking through the barrel and sight....