What choke do the police use in their riot shotguns?
That's why there is so much confusion around buckshot and chokes. The versatility of a shotgun and buckshot makes it the ideal tool for so many things. The home defender/cops would want a good, even man sized pattern at 15-20 yards. A cylinder/improved cylinder choke provides that. I want a basket ball sized pattern at 40-50 yards. If that's what anyone wants, a full choke is usually what they end up using. Don't take my word for it. Burn up $ and time figuring it out for your self. I already have.
I've seen 870 Police Magnums come with Cylinder, IC, and Modified chokes.
No cop wants a man sized pattern at 15-20 yards. Any agency fielding that shouldn't exist.
By man sized, I mean torso sized.
I'll be honest, I don't know what the police want with theirs. That's what I would want if that's what I used for HD. Defending yourself from a person across the room would require a different pattern than hunting deer out to 60 yards or so.
I'd be very surprised if many, or any of those 870 police magnums would hold a pattern tighter than my Benelli.