Doesn't matter much what size or type of shot one uses when you shoot them at 30 yards or less. Within reason, of course. I've double on geese with 3/4 ounce of steel 6's out of one of my 20 gauge O/Us. $6/box.This thread got me thinking so I pulled the trigger on a case of Boss copper plated bismuth, 2 3/4" 1 1/4oz #3/5. Also picked up a few boxes of their 3" 1 1/2oz #2s for late season geese, I'm excited to try them out! Bismuth seems to be the middle ground as far as performance to cost ratio goes, with steel on one end of the spectrum and TSS on the other.
This particular gun is a Beretta BL-4, made in 1968 with fixed IC/M chokes, so steel shot larger than 6s is not recommended. Weighs under 5# 14oz, so is a wand: