Big Whoop. My city has been using "patrol" riflemen for five years.
So has mine. Long Beach and Los Angeles have carried AR-15's since the North Hollywood Shootout.
As for the previous comments about the Ruger Mini-14. It doesn't have the accuracy at distances that the police need. I've shot one and my groupings started to really faulter after 100 yards, especially since i was using run of the mill ammo and not hand loads.