Where can I find statistics of the amount of gun crimes committed with unregistered guns?
Well.. You will not be able to find this statistic for a simple reason. In most states of the Union there is no gun registration. The only guns that are registered are those known as National Firearm Act weapons. There is a statistic for those registered guns. The statistic is that only one registered machine gun has been used in a crime since 1934, and that crime was committed by a police officer. If you want to look into something where you might be able to come up with a usable statistic, look into the number of crimes committed by Felons with firearms. These people are already prohibited from even having a gun in their hand, and yet we still seem to have a problem with them ignoring the law.