It could be pointed out that nationwide, police departments have been procuring weapons far beyond any conceivable need or legitimate use.
A city police department does not need a .50 caliber machine gun (one chief of police suggested it could be used against kamikaze-style aircraft attacks.) It would also be very hard to justify a water-cooled Browning .30 caliber machine gun.
A city police department does not need more than incidental quantities of high explosive. Nor do they need fragmentation hand grenades. Though dynamite cord is a quick way to cut through trees, a chainsaw is about as fast.
Police departments do not need rocket propelled grenades with armor piercing heads. Only very rarely do they need armored cars with battering rams.
Even SWAT teams are hard pressed to justify carrying AR-15 machine guns instead of just rifles and shotguns.
The worst part is that there seems to be no citizen review of what has been procured by police departments. Once they buy something like that, they keep it until it is unusable.
AR-15 = semi auto only
M-16 = semi auto (3 shot burst on some) and full auto