Pg. 27 "Gun shows are a special case of the retail sale of firearms. Unlike at other venues, both federally licensed dealers and unlicensed sellers sell guns at gun shows. While federally licensed firearms dealers perform background checks, unlicensed sellers are not required to do so. Gun shows are also places where buyers can choose to buy from the primary (firearms sold by FFLs) or secondary (firearms resold by unlicensed sellers) firearms markets. Secondhand firearms are far more difficult than new guns for law enforcement officials to trace to the most recent seller. This is because secondhand firearms likely have left the hands of FFLs, who are required to keep records, into the hands of unlicensed persons who are not required to keep records. Even if the secondhand guns are resold to an FFL, they are untraceable, because the trace will effectively end at the last sale in the unbroken chain of licensed sellers. The access to anonymous sales and large numbers of secondhand firearms makes gun shows attractive to criminals. In the ATF trafficking investigations reviewed here, gun shows were associated with the diversion of approximately 26,000 firearms. Trafficking of firearms at and through gun shows was more prevalent in the trafficking investigations submitted by the Southwest (22 percent) and Western (21 percent) regions when compared to trafficking investigations submitted by the Central (15 percent), Southeast (12 percent), and Northeast (8 percent) regions of the United States. A prior review of ATF gun show investigations shows that prohibited persons, such as convicted felons and juveniles, do personally buy firearms at gun shows and gun shows are sources of firearms that are trafficked to such prohibited persons. The gun show review found that firearms were diverted at and through gun shows by straw purchasers, unregulated private sellers, and licensed dealers.22. Felons were associated with selling or purchasing firearms in 46 percent of the gun show investigations.23. Firearms that were illegally diverted at or through gun shows were recovered in subsequent crimes, including homicide and robbery, in more than a third of the gun show investigations.24"

Pretty much there in black and white. Zero documentation required to accompany guns sold by private citizens/unlicensed dealers. Many of which were subsequently recovered from violent crimes. Seems like something that should be stopped to me.