PDF of the report
A Department of Justice report shows that only seven percent of nearly 300,000 state and federal prisoners who possessed a firearm during their crime purchased the gun from a licensed firearm dealer.
The report estimates that 287,400 prisoners had a gun on them when they committed the crime for which they are imprisoned, and a majority of those prisoners either stole the gun, found it at the scene of the crime, or bought it off the street or from the underground market, according to the 2016 Survey of Prison Inmates.