On a server I was on (0.3) they had all players weapon skill set to low when they joined, however if they had undergone training (i.e member of the LSPD) their weapon skill went up, I think this would help RP because how can a pizza boy be as good a marksmen as a SWAT officer?
People will think twice about starting a fight with the cops if the cop is extremly accurate with a deagle...and the criminals are not.