CB, the shotgun, especially the 12g, does more wounding than any other gun known to man. Not a man here that has hunted more than a season can say they don't regularly see and do themselves wound birds. Anyone really concerned about wounding would never hunt birds with a shotgun. The odds of a wounding hit bird are astronomically higher than an instantly killed bird, no matter the gun size or shot size. Factor in the shooter's skill, pattern density, bird size, etc. Do the math. You want fair, climb in the ring with a predator of your equal weight and don't bring any weapon...that's fair. Any other hunting is very much one sided, nothing fair about it.
The bird was as dead when it hit the ground as it would have been if hit with a howitzer...or a 12g. It's about shot size, not bore size.