First Episode of the new season is in, and SWAT won out over GSG-9.
For Mid-Range, i would go for the PSD with its compactness and large caliber round.
Close range, the Remington 870. Like the GSG-9 guy said, using a Solid Slug is more accurate that buck would be.
Long Range: Remington 700, that thing frickin blew up that gelly head from the inside.
Special: I'd go with the Stinger. Sure, a taser can take down a guy in seconds. But odd's are the stinger would be better for close quarters like what these guys would encounter often, plus it's indirect so you don't expose yourself.