I've called turkeys in for a buddy that hunts almost exclusively with a 20 ga. He uses 1 1/4oz #4, and the few he's taken didn't know the difference between a 12 and 20. Of course the shots were within 30-35 yds, which I consider about max for a 20.
On the other hand, we used to hunt geese at Izembek Lagoon in AK using steel shot (pre-bismuth/heavy shot days) and I have to say, I suggested more than once he should go with a 12, due to the 20's lack of performance(he's a better wingshot than I, but it sure wasn't evident on those waterfowl hunts) Some of the shots taken were well within 35 yds, but he'd have to pump 2-3 shots into the birds with steel to bring them down. Fortunately, he took my advice, at least for waterfowl.
IMO, the 20 is not a good goose gauge unless used with shot resembling lead in performance!
