I wonder why most multi-pump guns have the pump mechanism held in with roll pins. I'm sure there is a reason, I just don't know what it is. I have never taken a pumper apart but I'm sure I will try it eventualy. These roll pins are the only thing that intimidate me about it. I can just see myself wrecking the pump tube trying to get one back in place. I would like to hear from some of you with any tips or pointers you could offer on the subject. Thanks!