What works for me in my 20 gauge, is I get 1220 speed,1 ounce of shot in 7.5 or 8 shot. I go with usually a light modified choke. The light modified is .005 looser than a true modified. If I'm shooting my O/U I will have an improved cyclinder in the bottom light mod. in the top for quail and hungarian partridge. Chukers; I go same size shot and speed, but light mod bottom and true mod in the top. it seems to me they take more of hit to bring down.