The government of PR just voted on and send to the governor a bill allowing people to defend their property with no liability for death or shoot action. As part of the bill your residence was extended to car, boat and other places where you could relax and be a victim. It is unknown if the governor will sign it into law.
In PR if you shoot at someone, even pulling the gun out could land you in a heap of problems with the police and the judge, regarles of you defending your property or your life. In many cases is you shoot at someone, better say nothing and call your lawyer. The above if it becomes law may make it reasonable to own and use a gun.
In PR the government thinks that having a gun is a privilege and has the strongest set of rules I am aware of in the US. Never mind the US constitution, PR is selective as to what a right is unless it is convenient. Nobody has taken them to Federal court about their right to own and carry weapons.
PS. to my knowledge your license to own and carry a weapon from any of the mainland states is not any good in PR.
http://www.noticel.com/ahora/aprueban-m … /714321724
Current weapon law (404) (Spanish) ruling ownership and other subjects regardless of the above news: http://www.bullseyegunshoppr.com/ley404/