Being a handgun, or long gun expert is not a qualification for being a police officer. Every police officer carries at least one handgun, and possibly a rifle and / or a shotgun. Their department insures that each officer is qualified with the use of these weapons, and the legal details of when each weapon may be used. This does not make any of them an expert. I dont know why anyone would assume that any of them is an expert.
Some policemen are firearms enthusiasts. Most are not. These inthusiasts arent experts any more than those who are not. The police recieve more better training than most people. (I know I'm going to get flamed for this). Police training tends ro be reality based not worst case scenario based.