It actually wan't too hard to do, and yes, it fulfilled my definition of "fun" at the moment.... Once I realized the only variables were velocity and SD (and that they were both linear variables), it was just a matter of figuring out the constant they were using.... I've read several places that those are, indeed, the only factors governing penetration, assuming a constant nose shape, no distortion, and no tumbling.... all of which happen in the real world.... Pellet choice is still a matter of delivering the most energy on target downrange, and then having the target absorb it as completely as possible once penetration to the vitals has been achieved.... None of those things are easy, and they tend to be mutually exclusive to a degree.... However, they apply to all calibers equally, so the basic math still give a valid comparison....

Bob