You outta let me trade you out of one of those Canucks, I've got lots of paper shells in duplicate. Are they the ones with the big high brass?
I've shot 7 1/2's at ducks several times in the past, they're sure death inside 25 yards. I had some 3 inch ones that a friend gave me years back, I think they were 1 7/8 loads by Federal. The Winchester Super Pigeon load in copper plated 7 1/2 was hell on close range ducks as well.
I bought a whole case of Winchester Mark 5 1 1/4 ounce of 7 1/2 awhile back actually. Got them for $4 a box, quite a bargain. Don't know what I'll ever do with them but at that kind of price heavy loads are hard to pass up. Will probably shoot them up at live pigeons but it will take me awhile as I don't shoot flyers that often.
A lot of the old green timber shooters in Arkansas used them because that kind of shooting is all real close range unless you're tree topping. Had a friend here in Michigan who used to do a lot of sneak shooting tell me that his father always used heavy loads of #8 out of the sneak boat again because the ducks were usually so close.
Don't know as I'd go that small on geese though, I think really abouta #4 is as little as I'd feel comfortable with. With that light shot you've gotta get them in the head or you're not gonna kill them. Those little pellets wouldn't even break a wing unless they were right on top of you. Your mentor was probably one of those old timers that just didn't miss, I've seen them in operation and it's a wonder.