There's a small cult of the 20 in Russia, with the followers claiming against all evidence that the bore develops higher velocities at target. It might be powered by the myths surrounding the legendary 'promyshlenniky' (Siberian trappers and market hunters), who were supposed to prefer small bores (as a matter of fact they did use a lot of small bores but mostly because the socialist economy didn't supply them with anything else). But I doubt that more than 1 hunter out of 20 uses a 20 for hunting.
