Does anyone have any experiance or know what if any federal laws exist regarding the theft of firearms or are they just treated as general stolen goods?

I had a stolen Govt. Model recovered by Phx. P.D.  They arrested the fuck on some other charge, but no charges were pressed for Posession of a Stolen Gun.  At least i got it back in good shape. (about a year later)

This what you're looking for?

18 USC 922(j) It shall be unlawful for any person to receive, possess, conceal, store, barter, sell, or dispose of any stolen firearm or stolen ammunition, or pledge or accept as security for a loan any stolen firearm or stolen ammunition, which is moving as, which is a part of, which constitutes, or which has been shipped or transported in, interstate or foreign commerce, either before or after it was stolen, knowing or having reasonable cause to believe that the firearm or ammunition was stolen.