The registration of weapons can do only so much to stop these types of tragedies; their availability for misuse by anyone - including people not registered as their owners, as happened recently in Newtown, CT - is the key issue.
We can use the Second Amendment to frame effective gun control.
1. Limit legal firearms in typical citizens' hands to those that would have been familiar in times when the Second Amendment was ratified - single-round, bolt action hunting rifles are the modern equivalent that were intended for use in militias back then. These are used rarely in mass murder tragedies.
2. For any other kind of firearm, citizens must be active members of the National Guard and comply with strict regulations on the use, storage and monitoring of any home-based weapons.