I shoot a goodly amount of 1 1/4 oz. loads at ducks . . . bismuth. I lean towards the heavy side because it's so easy to lose a wounded duck. It'll dive, grab a root in its beak and hang on until it drowns. I've seen woodies do it many times.
I'm much, much less likely to lose a crippled dove, so my dove loads range from 3/4 oz. in .410, to 7/8 oz. in my 20s, to 1 oz. in the late season in my 16s. Doves in December and January are much more tenacious of life than the early season birds.
I seldom use a 12 for doves. I love my 30" and 32" barreled 16s in the late season.
I want to make a correction to my opening statement in which I said "tens of thousands of doves". I realized after reading another post on the thread that what I wrote was inaccurate. What I meant was "over ten thousand doves". My apologies for my carelessness and inaccuracy.