9.—(1) A person may, without holding a firearm certificate, have in his possession or purchase or acquire an air gun.
(2) Sub-paragraph (1) does not apply if the air gun is capable of discharging a missile so that the missile has, on being discharged, a kinetic energy in excess of one joule.
(3) A person who is under the age of 18 may not by virtue of sub-paragraph (1)—
(a)have an air gun in his possession without a firearm certificate unless he has attained the age of 14 or is under the supervision of a person who has attained the age of 21;
(b)purchase an air gun without a firearm certificate unless he has attained the age of 17.
(4) A person may, without holding a firearm certificate, have in his possession or purchase or acquire ammunition for an air gun.