It's all one thing. The law talks about sporting purposes, but with respect to handguns the BATE (I think) came up with a points system to determine which handguns were "sporting" and which were not. I'm not sure of the details, but things like safeties get you points, but being big does as well. The Glocks in the less powerful chamberings were likely too small to be importable.
Isn't the 'sporting clause' balony from the 1968 law? I sure wish that one would get repealed.