RE: Shot size for smaller birds
I mostly hunt Grouse and Woodcock, and have found 7 1/2 's to be sufficient for the chore. Later in the season, as the forest thins, and the grouse become a bit jumpy I will back the 7 1/2 's with a 6. My 20g is choked sk/ic, while my 28g is chocked sk/sk.
Should I hunt pheasant, or quail around here I would use the same loads, except I would always go 7 1/2-6 on pheasant whether it be early season or late, and just 7 1/2's for quail.
I prefer 1 ounce loads, but ussually buy whatever is available.
These loads, and shot sizes might seem a bit light to a hard core pheasant hunter pursuing wild birds, but around here all the pheasant and quail are released birds.
Most important is having a gun you shoot well, and putting the pellets where you need them.