I used one on a Logan s16. The laser fitted below the barrel, so targets less than zero had the dot showing under, and targets further showed the laser over. It was a rough guide, but due to the scope height above barrel was effective, aim where the dot shows with the cross hair on target, close in, the cross hairs are higher than the bore, further away the aim point needs to be higher. Plenty of practice at known ranges is needed to learn the aim points! David