New shotgun?

If you shoot BBB or BB it should be fine for decoying geese. Shot an 1100 2 3/4 growing up.

Goose hunting can be filthy. If there is any chance you'll be hunting in muddy fields then you definitely should make a pump your #1 consideration.

I got a browning bps for goose, saltwater duck hunts. Very pleased with it.

BPS 3.5"

I went on my first goose hunt last year with a remmington 870 super mag. I was shooting 3-1/2 BB, and after 18 shots, I had a bruise on my shoulder for a week.

I'd suggest the super mag for the 3-1/2" option. I have an express 2-3/4" - 3" with a 26" barrel and love it, but for geese, I go with 3-1/2" and 28" barrel.

I gave up on 3.5” shells a few yrs back, a pump w/ 3.5 is not fun. Learn how to shoot and use a good quality 3” shell w a minimum of 1500 fps. I hunt canadas which are a lot bigger than specks/snows and I shoot a 3” shell ranging from 1550 to 1700 fps, you also have to pattern your gun and find out what chokes work w/ various shells. Im not sure I would drop down to a 2 ¾ shell. Some of the folks I hunt w use 3.5s and typically I out shoot them ... its generally the indian not the arrow.