WOW, fast response. Right now I have a Pellet rifle scope on my AR. Yes, I said PELLET RIFLE! BUT it is rated for unlimited full auto fire! It's a 30mm Beeman SS4 scope that I love. The rifle (flat top of course) has the regular ar15/m16 front sight and the carry handle comes off with two thumb screws. It works fine for me before I got the scope but I just thought I could put the rear BUIS on it for "In Case".

My concern was finding the right "Rail" cause the regular hand guard on it isn't all that long. PLUS it attaches at the rear with a collett (?) ring that is spring loaded and holds on the guard. How do I go about finding the right size handguard?