There are probably some pro-life protesters who've been charged with same crime stemming from a protest.
Is it enough to fail a background check?
Or was he a meth user as has been unverifiably reported?
The things that will get you denied are normally something to do with some type of violence or battery charge, drugs, stalking type stuff. Then you can appeal it/explain yourself and get approved. Really not that big of a deal.
What I really find interesting about the system is, as a gun owner, why does the FBI manage the NICS system? Why doesn’t the agency responsible for firearms do it?