In Australia police do go into homes and check. They have random spot checks to make sure guns and ammunition are stored correctly (locked up separately). The

In Australia police do go into homes and check. They have random spot checks to make sure guns and ammunition are stored correctly (locked up separately). They check the guns owned and make sure types and serial numbers match up. And if you no longer have a valid reason to keep them (you quit regularly shooting at a club/range), they will ask you to hand them in and you're no longer allowed to keep them.