I wonder if the 90% bought the "40% of gun sales are at gun shows without a background check stat"?
The survey (NSPOF of lawabiding gunowners) that found 60% of gun acquisitions are at gun stores or pawnshops with FFLs also found that gun shows plus fleamarkets were only 4% of all gun acquisitions (and they are a mix of dealers and private sellers).
The Bureau of Justice Statistics survey of state inmates (criminals) found that of gun possessing inmates 0.7% bought guns at gun shows and 1% at fleamarkets.
I think if the supporters of universal background checks knew that gun show sales w/o background checks are not 40% of the gun market, but are a small fraction of general gun acquisitions and a sliver of criminal acquisitions, the UBC support would drop.