Where any person–

(a) who is not authorised under this Act to have possession of a firearm has possession of a firearm; or

(b) has possession of a firearm which that person is not authorised to possess under this Act–

and that person voluntarily brings the firearm to a police station and surrenders it to the Commissioner, no action is to be taken against that person in respect of the unauthorised possession of the firearm by that person.