This is why I take the results of any 'study' with a grain of salt. Everyone (both sides of the aisle) manipulates the information to show what they want to see. There simple are no unbiased 'studies' anymore.
An interactive map created by a New York public radio station is being picked up and spread by news outlets as a meaningful tool for understanding interstate gun trafficking. Based on state firearms trace data summary reports provided on its website by the Bureau of Alcohol, Tobacco, Firearms and Explosives, the widget presented by WNYC allows users to click on a state and see how many guns traced were originally purchased on the retail market there and how many came in from other states.
http://www.examiner.com/article/crime-gun-trace-map-withholds-key-data-needed-to-draw-meaningful-conclusions

What is the point of rules that are not enforced?