The Weapons Envelope will deform and may grow in one area while almost completely disappearing in another. It should go without saying, the target will attempt to put the less effective portion of the Weapons Envelope towards you. Remember this as well for the Defensive BFM chapter, what works for them will work for you too. Most missiles will have similar Weapons Envelopes, RMIN and RMAX figures being the primary difference. As I said before, Rear Aspect Only missiles would not have the forward portion of this diagram.
Guns are the other exception.
There is no minimum range on a bullet. You can have your nose half way up the targets tailpipe and still shoot guns. The problem here is that you may end up killing yourself as pieces of your opponent start coming off and smacking your aircraft. Most recently released sims as well as some on the way have begun to model this aspect of air combat. So beware just how close you get before you take the shot.