So in other words, besides the lack of backing up your claim, now you're actually bolstering the #'s that still more crimes have been averted with the use of gun, but you're now speculating that those simply went unreported. You do realize that the FBI stats are supported by actual reports taken by law enforcement, who would be in a position to identify a faked incident, and thus be removed from such stats.
So, back to this supposed claim about some Republican(s) passing some law, at some time, preventing the FBI from releasing gun statistics. As you said, you should know this