Can i register my gun in AZ if i don't have any paper work of it?

Can i register my gun in AZ if i don't have any paper work of it?And if so how can i register is so i can open carry its around for my safety? Got it off a friend some time ago he also didn't have any paper work on it and now his gone and his not coming back anytime soon can some 1 help?...Guns not stolen according to HotGunz.com