Create a national gun registry that can only be accessed after getting a search warrant from the courts.

There should be a national gun registry, but the information contained in that registry should only be available after vetting that request through the courts.

The registry should not be used as a way to track down legal gun owners who's guns become subject to new laws, but only in criminal investigations.

This should be a simple system with only basic information to make sure it is not a large tax burden. Name, address, gun serial number and type, any special category applied to the gun owner (law enforcement personnel, etc.)