Arbitrary, Illogical
So all other factors being equal, large-caliber handguns are more easily importable than small caliber ones? That is stupid. Totally stupid. How is that related to safety? If you want to distinguish between hunting guns and combat guns, you can't tell by the caliber. You'd have to look at accuracy. A .22 makes a great small game gun, but a .45 acp isn't a good choice for hunting anything. A .45 acp could be a good target pistol, though, but then so could a .32. Yet the .32 is strongly disfavored and the .45 gets a bunch of points in this rating system?
Oh, maybe the caliber restrictions were meant to discourage small guns? Well if "small guns" are what you're after, why not just delete all references to caliber and go with overall size. Height, width, and length. The factors that make a gun concealable.
This rating system ought to be struck down by the courts as lacking even a rational relationship to the purpose for which it was intended (to keep poor blacks from arming themselves).