Something I found a while ago I thought some of you folks here might find interesting. I thought it especially suited, considering cast bullets can lean more towards the "slow and heavy" side of things. I figured it fits as well here as anywhere else.
http://www.kineticpulse.com/kp.html
"A study in bullet impact". Killing Power, or Kinetic Pulse, or just plain KP. Basically, this guy (James N. Hall) formulates a way to consider both kinetic energy and momentum in the analysis of a bullet's terminal performance. It's a bit of a long read, so I'll try to give a basic idea of it here:
The volume of a cavity created by a projectile when it impacts something (clay, for instance, or a body) is proportional to its kinetic energy multiplied by its momentum. The KP is given in terms of the volume. The more kinetic energy something has, the more "splash" it has; and the more momentum something has, the deeper it tends to penetrate. So you can view the displaced volume as a cylinder, with the kinetic energy representing its circular cross-section, and the momentum representing the "depth" or "tallness" of the cylinder. You can then keep those dimensional proportions in consideration when assessing KP for different targets (thick vs. thin).
That's a very basic idea. He has lots of math on it, did stuff with units I don't mention here, etc. Lots more is said. One thing he doesn't do is consider different diameters/shapes of projectiles - not because he forgot, I am sure, but probably because he hadn't found a way to represent it. He says that the projectiles compared with this method are presumed to be identical (except in mass). He gives lots of examples and data for a large variety of cartridges.
Overall, if you're at all interested, I suggest you read it. I give a rather shoddy portrayal here. There are also links at the bottom of the page which are interesting (a KP calculator among them).
I don't think this is the ultimate word on anything, but it's interesting, and I think it is worth having in mind. Hope you enjoy!