hey, my best friend picked up his g19 at a gun show used, its a gen 3. i eyeballed it when he bought it and it looked gtg although a bit dirty. it fires fine, no issues... but one day we were talking about operation of it and i was telling him that slingshotting the slide is your best bet etc. etc. he says... my slide slams closed when i slap a magzine in... that didnt sound right to me... so i checked my own g19... sure enough mine doesnt do that and my friend is concerned that he may have a bad part somewhere he needs to replace. so whats the verdict... whats wrong with it and what does he need to replace?