Handirifle, it works just like a Unertle or supertargetspot. In fact I have seen them in use with the return spring on them. Unertle made them but I have only seen a few. I had one But it was a short one and you had to have a fixed front sight at the end of the barrel. The type JoeB has shown is the better one. With a two piece setup getting a concentric sight picture that is at the same time zeroed is a pain in the butt. You have to chase all kinds of Scope block heights and manipulate the Front sight location. I got so frustated with mine I gave it away. The Long full length is better. And the sight picture is so sharp with really good contrast. Well enough, HTH Regards, FITZ