Yes they work but there are better ways to do it. We take the bolt out of a gun and look through the bore and align it on a light on this cell tower about 3/4 mile away. Ten we line the scopes crosshairs up with the light without moving the gun at all. This normally gets us really close. Now some guns you cant do this with sicne you cant look down the bore. Preatty much any pump, semi auto, or lever gun this is not possible.