Recon Brothers got a helpful video to help you zeroin your optics without the need to fire our airsoft gun. For those who do not have backyards or live in the cities, this is a video to bookmark... "Zeroing an optic on an Airsoft gun is always difficult unless you have some sort of shooting range with no wind influence. At least that was the case until now, because we've developed a new method which allows you to do it just at home."