Can say however, {before I found out it couldn't be done(http://www.getphpbb.com/phpbb/images/smiles/a_whatsthatyasaysonny.gif)}the gun thatI used to take the most SC greys withwas an old open sightcrosman 760 pumped 5 or 6 timesbetween 5 and15 yards. Probably just under 500fps with the old daisy pointed pellets {now sold as gamo pointed} but no over penetration since never found any exit wounds. Very rarely required a follow up shot,either.
Headshots would just knock them right offa treeusually without a twitch . . .(http://www.airgunhome.com/agforum/images/smiles/ahhhhh.gif)