Terminal Ballistics 101....... Given a good HP. The faster the bullet,the faster expansion,the less penetration. The CORBON 165's at 1250fps will penetrate just about right,slow them down to 1050 and ???. The down side of the CORBON ammo is,too much recoil for double taps. Look at the CORBON ammo's HP cavity. It's huge. The bullets velocity is high. It all evens out. With the regular thick walled HP's out their,I would be suspect of overpenetration. The heavier(200&230gr)Hornady XTP's especially. At the slower short bbl velocities I suspect that they would penetrate very deeply. Not sure about how completely or how evenly they would expand. I feel that the consumer has no way to really tell what the bullets outta our weapons will do when entering human tissue. The tests that are done are,for the most part,done to sell ammo. The other info that is compiled(Hatcher,etc.) has a huge ammount of variables involved. In the end,all we can do is use our understanding of ballistics and pick the ammo that is powerful enough but not too powerful,accurate enough out of the intended firearm,cost effective to carry AND practice with and above all........ looks pretty sittin' in the cylinder or mag. ----------