I use #3 buck, pellets are 24 cal and at 75 cover tail to nose. I do not search them up after I shoot, but they never come back, an ounce of #3 buck is hard to carry.
I use a 391 Beretta 20ga with a 20" barrel, IC choke, a palm switch mag light cowitnessed for pattern on the light circle on a pond. You pick up about 3 more pellets with a 3" VS a 2 3/4" shell. The #3 is a balance between numbers and impact power.

“To expect defeat is nine-tenths of defeat itself. It becomes a self-fulfilling prophecy. It is best to plan for all eventualities then believe in success, and only cross the failure bridge if you come to it."
Francis Marion - The Swamp Fox