My guess is that 99% of those declined were either errors or people who had no idea they had committed some relatively minor crime in their past.
The number of hard core criminals actually kept from obtaining a gun by any means would be close to zero.
I should have said “people who had committed some minor crime in the past that they didn’t know would block their over the counter purchase.”
Or mistaken identity. My buddy found out he was 6’5” tall and had a warrant out for his arrest in Texas. He is 5’7” and lived in Okolahoma when he “commited” the crime.