Well we had everything from a Moose-gun with scope to a pocket derringer. A couple years back I reported them all as missing presumed stolen from our house. Even tho most were pre-registration types, they have equipment in their vans where they can cruise down the street and it will pick up if there are any weapons in someones house or yard. If they find them you get a fine, jail or both unless you fess up and turn them over.
Unless they are in a waterproof something lead lined under your dock or 20 ft up in a big old hollowed out tree etc. If in your home, they will find them. Ammo also has to be sequestered, as is black powder.