In Britain citizens had until a certain date to hand in the guns or give them to a gun club. Then the government personally confiscated all the banned guns which weren't turned in by the owners.
We could probably wait another 50 years and Britain's gun crime won't change much. Mostly because problems didn't come from legally owned guns but from guns smuggled into the country by the gangs.
Because the gun/weapon laws here are useless and we're better off without 98% of them.