They do not get them in stores so waiting periods can have no effect on them. See the Wright summary above. Probably not much to implement registration. Many states already have de facto registration. Registration has never been proven to have any negative effect on the crime rate in a given state.
Bans are simple to enact but impossible to enforce save for raids on people's homes.
See the history of Fidel Castro's Cuba, Hitler's Nazi Germany, Stalin's USSR, Mao's China, etc. if you need examples. The opposite appears to be true. Places with severe handgun restrictions or gun prohibition such as New York City and Washington D.C. have the highest handgun homicide rates. Conversely some states that have recently liberalized firearms carry permits have demonstrated reduced murder rates. More than 100,000 Floridians now have carry permits and fewer than a dozen have had their permits revoked for abusing them.