Had a really bad experience with Winchester #1 16g buckshot last winter. I called a coyote in the treestand I was hunting from and flattened him 4 times at ranges from 15-25 yards. Each time he went down like a stone (the second shell cartwheeled him) but within a minutes was back on his feet. I tracked him for over an hour in a frozen swamp, hit him twice more before killing him at under 5 feet with a head shot. When we skinned him we found that none of the many pellets that hit in the torso penetrated, all I was doing was knocking the wind out of him everytime I flattened him.
The temp was -15C that morning so that may have been the cause for the poor performance of the shells. This spring I found a store with 4 boxes of Remington #1B 16g still in stock so I bought all of them. I'll be shooting anything other than winchester 16g buckshot if I can find it.