Private gun sales, a point of information [View all]
(According to the figure at the link) Nine states have UBCs for all gun sales: California, Colorado, Connecticut, Illinois, Massachusetts, New Jersey, New York, Oregon and Rhode Island. Six others have UBCs for handgun sales: Iowa, Maryland, Michigan, Nebraska, North Carolina and Pennsylvania.
Handguns are the most common type of gun used in firearm deaths. That leaves 35 states without BGC laws on sales between private sellers.
http://www.governing.com/gov-data/safety-justice/gun-show-firearms-bankground-checks-state-laws-map.html
Known as the "gun show loophole," most states do not require background checks for firearms purchased at gun shows from private individuals -- federal law only requires licensed dealers to conduct checks.
Under the Gun Control Act of 1968, federal law clearly defined private sellers as anyone who sold no more than four firearms per year. But the 1986 Firearm Owners Protection Act lifted that restriction and loosely defined private sellers as people who do not rely on gun sales as the principal way of obtaining their livelihood.
Some states have opted to go further than federal law by requiring background checks at gun shows for any gun transaction, federal license or not. Five states, most recently Colorado and Connecticut, mandate universal background checks, an even more stringent standard that imposes background checks on almost all gun purchases, including over the Internet.
Even in states that do not require background checks of private vendors, the venue hosting the event may require it as a matter of policy. In other cases, private vendors may opt to have a third-party licensed dealer run a background check even though it may not be required by law.