Consistent killing range of a shotgun is not based on the penetration of a single pellet. It is rather based on a pattern sufficiently dense to ensure a lethal hit with pellets having adequate energy to penetrate. Therefore with the same number of pellets in the entire pattern, the one having a higher central concentration would have a slight range advantage with a "Center" hit. It would, of course, require a more accurate shot placement, with less room for error. Yes its based on physics, but there's more to it than just individual pellet energy. "IF" we were speaking of a single hit then a .22 short would be a far better killer than any of the above-mentioned loads, if legal & provided you were a good enough shot to place it where you wanted it.
Interesting. Roster's steel shot lethality test on pheasants--using 1 oz 2's, 4's, or 6's, shooters didn't know which they were shooting--showed that 2's were the best choice, producing dead or immobile birds at ranges up to 50 yards at a rate of 76.9%, compared to 65.7% for 4's and 62% for 6's. My guess is that the 2's came out on top because the other 2 loads lacked sufficient penetration beyond 40 yards, while hits by just 1 or 2 2's would still result in a dead bird. (Pattern fails before penetration, as the old saying goes.) Maybe the most surprising part, however, was that based just on those birds shot inside 40 yards, the 2's still were superior: 86.5% to 73% for 4's; 75% for 6's. Makes me wonder whether there was either more "shooter error" with the 4's than the other shot sizes. That or else the 4's didn't pattern as well as the 6's and 2's.
Miller, I don't know whether you've seen this study. But unlike the Thomas recoil stuff, this one goes into great detail on how the study was conducted. I have it hard copy with no internet link, but I'm pretty sure it's on line somewhere.
