Swampman,
The best ammunition is by far is Nitro Company Ammunition.I have a 16 ga made up with a ventrib,screw in choke tube,ported,I even have in chambered for a 3 inch mag 16 ga(NU-LINE GUNS).These shoot really good out of my gun.They are 2.75'' with 1 7/16 oz. of #4,5,7 HEVI SHOT at 1220 fps.These loads are buffered so your barrel bore isnt scored by the hevi shot.This is custum ammo and isnt cheap but its worth every penny.I have a 12 ga shooting a load similar but in 3.50'' and it will put in upwards of 250 pellets in a 10'' circle at 40 yards.The 16 is putting 150 pellets and up.This is fantastic for a 16 ga.If you want the best this is it.Look them up on the web and keep in mind he can make your load anyway you want like #4,5s,or 6s.Hope this helps.
WOODCHOPPER