He shot a few cattle to determine that. I've shot a lot more, but smaller critters and I agree. I've also noticed that smaller diameter hp bullets need more velocity in order to expand reliably in flesh and blood and that in no way can a jhp expand at less velocity than a lhp of the same caliber, weight, design and velocity. So when you say you cant get a lhp to expand, it's not only the hardness of the alloy, the diamater and velocity of the bullet must also be taken into account. I"ve done no real experimentation of hp cavity design, but the inverted hollowbased wadcutter, when you can get it to not tumble in flight, expands well in water at 900 fps. The little post in the nose cavity of the first .38 Hydroshoks was put there to prevent the bullet's tumbling. They also expand in water at 900 fps. I've had quite a few bullets NOT expand in animals which did expand in water. The lungs are just air sacks, and you need fluid flowing into and out of the nose cavity in order to "peel back" the lips of the hp. Hair, skin and clothing debris can also prevent a bullet's expanding in a critter, if its velocity is marginal for expansion. I dont trust 9mm jhp's to expand reliably in flesh at speeds under 1300 fps.