i was just wonering, when ellie shot dan there was clearly an exit wound. richie was right in front of him, so why didnt richie get shot? 
a lil strange dont you think?
Maybe by the time the bullet passed through his body it was spent and didn't have enough velocity to do any further damage.
Well, I think there are a lot of things that can, and should, be chauked up to good old TV magic and I think this is one of those cases. Would a bullet form that gun go clean thru a person at that range? I'm sure. But the way the scene was shot was done for dramatic effect, not to prove a point. But, who knows, this is LOST. TPTB might have given us a hint. But at this point, I have to go with TV magic.