I apologize for being mostly retarded. Anyhow I am the proud owner of a USP .45 and P2000SK but I want to "kick it up a notch." I've never owned any class 3 weapon but I think I've got a understanding of the process. What I am in dire need of help understanding the various versions of HK and HK Clones/Rebuilds. Like what is a "rebuild?" To give you something to work with I'd like a MP5 or MP5k. Certainly a never opened straight from the factory pre 1986 would be nice but hard to come by. What options do I have and what kind of price range am I looking at? Also, what if something breaks, what can or cannot be legally fixed? Thanks and I again apologize for my newbie-ness.