If you're stopped by a CO in the bush and you have a firearm, in Ontario, you are assumed to be hunting. No hunting licence or using a firearm chambered in a calibre not suitable for whatever game is in season can get you charged with hunting without a licence and hunting out of season. Having targets with you might, I say again, might avoid this. Having targets likely will avoid it as long as where you are shooting is safe. Crown land is used by all kinds of hikers, picnickers and other riffraff who don't have to pay the Outdoors Card Tax. Be very sure of what is behind whatever backstop you're using.