Puerto Rico has the most strict Gun Laws within the good ole US of A.
1700s Wheellocks and Snaphaunces are locally still considered firearms, and their possession sans a gun's permit is considered a felony.
You have no idea how many historical weapons have been laser-sectioned and thrown to the sea depths...I remember a $40K Borchardt that went that way.
If a gun is illegally owned (license lapsed for three years) , it can not be legalized _ever_.
Historic Reenactors need a special dispensation from the Police Comissioner just to fire blanks...
OTOH, illegally, you can just go to the nearest Public Housing Project and buy an AK-74.