The 300 meters is applied in provincial parks. If another road has it, then it is a specific case, as it is not the norm. For any other maintained road way, meaning graded and so on, as long as you are beyond the ditch in most cases you should be legal to shoot...........keep in mind though, that it may be private property that you're walking on to fire your firearm from. So make sure you know about the ownership of the land as well, and gain permission if required.