Skull shots are not a good measure of performance. While the skull is reasonably thick, the curves and angles deflect rounds more often than you might think. Even high velocity rounds from rifles are sometimes deflected off the skull and cause only superficial damage. But only sometimes.
From personal experience I can tell you that a SWC .357mag bullet will shatter bone. It may glance off something like the femur, but if it does, its because of the roundness of the bone, not its size or srtength.
I saw a 270lb man shot in the shin with a 160gr SWC driven by a hefty charge of H110. Slight downward angle. Perfect .38 cal entry hole, ragged exit wound in the calf, about the size of a half dollar.
That bullet shattered 17cm of bone, reducing it to chips 1/4" long or so.
There is no doubt in my mind that it would have done about the same thing to the thigh bone. And had that bullet struck a rib, the damage from secondary missiles (bone shards) would have been considerable.
A flat point and power destroys bone. A rounded/pointy tip and less power usually deflects to some degree. It may break the bone, but seldom shatters it like a SWC can do.
Even high power rifle rounds can deflect off bone, sometimes. Its not just a matter of power (velocity), but also of the angles of contact involved.
For example, the bullets that work best against the skulls of elephants and water buffalo are solids (non expanding), rounded noses, and moving about 21-2200fps. They smash through a high percentage of the time. The same bullets moving considerably faster (24-2500fps+) show a much higher percentage of glancing off and not penetrating. Velocity plays a big part, and too much is as bad as not enough. The same principles apply to the lower speeds of handguns, against smaller animals. There is a "sweet spot" speed where the bullet will smash through, faster or slower means more likely to deflect.
This speed will be different for each kind/shape of bullet, and the type/shape of the bone being shot through.
