There is a lot of misinformation, urban legend etc. around the NICS stats. Here is a great resource for NICS ops, including background check volume, denials, appeals, and reasons for being prohibited. I am not
in favor of universal background checks. We need to get our facts straight though.
A couple of things jump out at me:
This is from Nov '98 to Dec '11 (not 1.5M like Obama said in a speech recently)
Denials as a percent of Transactions
In 2011 there were 16,454,951 transactions and 78,211 denials. Most people probably know whether they will pass. We also don't know how many purchases were attempted but were not processed by the dealer due to disqualifying answers on the 4473
Of all Denials, how many were Reversed
Of 78,211 denials, 17,203 were appealed and 3236 were overturned. Note this is a much lower number of denial reversals than you sometimes see.
Link to the report is here, take a look. What jumps out at you?