21.—(1) The restriction imposed by section 17 of the Principal Act on the importation into the State of firearms shall not apply in relation to the importation of a firearm by the holder of a firearm certificate in respect of the firearm which is in force.

(2) The said section 17 is hereby amended by—

(a) the deletion in subsection (3) of "(not exceeding six months)", and

(b) the deletion in subsection (4) of "(not being more than one month)",