What M29 said. The points system looked at barrel length, grip size and even grip type with regard to it being a "sporting arm" or just a very concealable pocket pistol. Very small guns (I forget the exact dimension) with short grips were import banned outright IIRC. These rules still apply and that is why many Makarov and Beretta pistols imported after 1968 have a thumbrest on the right grip, for target shooting as a "sporting arm". Uh-huh.