Hi Finnish,
I had a "prolonged borrow" of one and I found it was good for rechecking your zero. I had a target at 35 mts and when I knew my rifle was zeroed at 100mts , I could check by lining up crosshairs on my 35 mt target and noting the position of the laser, making sure it remained at the same point.
The dot did not line up with the crosshairs on the target if that makes sense.
PS I should have said that it was on my .223 and when zeroing it was only good for getting on to paper.