(3)Whenever any person has in his possession any firearm without such name, number or other identification mark on which such name, number or other identification mark has been obliterated, removed, altered or forged, it shall be presumed unless the contrary is proved, that he has obliterated, removed, altered or forged that name, number or other identification mark:Provided that in relation to a person who has in his possession at the commencement of this Act any firearm without such name, number or other identification mark stamped or otherwise shown thereon, the provisions of this sub-section shall not take effect until after the expiration of one year from such commencement.
