Effective background checks for all is a big one. Nominal fee for FFL's to conduct for private sales. I am more skeptical of magazine limits and would set it at 20 and not have a magazine extend past handgun grip as they are more easily concealed. I would even institute a voluntary license similar to a CCW where you have a very thorough background check and show training and show this to avoid having to perform NICs at time of purchase. This can even be set to levels for different types of weapons. Ammunition I do not think is a big issue as one box can be enough for a mass killing. Target shooters buy in bulk.