It is to late when they are knocking on your door, this is the typical Canadian way, to wait until it is to late. I can not advise you to break the law, if you own restricted or prohibited firearms there are records, these records are badly flawed and if you are prepared to go toe to toe with the authorities and argue the point you may well get away with it. My advice is to follow the law until such time as your legally possessed non restricted firearms are called in. Now I can not advise you to break the law, but I have heard that Mike from Canmore (at least I think it was him) is planning to take a shovel and a GPS when he takes his soon to be restricted semi auto rifle on one last shoot!
Time to get political active now so we are not backed into a corner. Fight politically now, you have nothing to loose and everything to gain.