Not 3gun, but I quail hunt with my Rossi Overland Coach gun with 20" tubes and use the daylights out of my 18-1/2" 870 (it has rem chokes) and will be my next 3gun shot gun. Knowing your tools is key, with the 870, I won't take long shots because I know how it patterns at distance. Just make sure that the plug is in if needed. I have been bugged in the field by other hunters and the game wardens, but I let it roll off like water on a duck's back.
Key word here is knowing how your shotgun patterns at range with your hunting loads and the chokes that you have, steel and non-tox do perform differently than lead.