I hate to sound stupid, but just because I own 8 or 10 HK longguns, I know that does not make me an expert. And my knowledge leans more towards the 91/ 93, and USC/ UMP. So my stupid question is what is the difference between an 89 and 89 reverse strech. I own a Vector MP5/.40 , but not any 89's. I don't know if it is or is not considered a "stretch". What is a "reverse stretch"? I know this is an easy one for chopstix or gillie.