I have a Kimber Ultra Carry 2, I have put many different rounds thru it like magtech, pmj, winchester, hydra shok, blue dot, and a few others and haven't had any issues. Well, I take that back, the hydrashok's didn't expand. We were out in the field and had some drywall left over from a job. Just to check penetration we lined up 5 walls with about 5 inches between them and a heavy block at the end, from about 10 and 20 feet they went thru all 5 and into the block but held form. So I'm thinking that the 3 inch barrell on the weapon doesn't allow enough barrell length to get the rounds going fast enough to expand. Do you guys have any suggestions as to what round would be best to "stop" an assailant?