“(3)

A person shall not be guilty of an offence under section 3(1)(c)(i) of this Act by reason of any smooth-bore gun for the purpose of killing any deer if he shows that the deer had been so seriously injured otherwise than by his unlawful act or was in such a condition that to kill it was an act of mercy.

(4)

A person shall not be guilty of an offence under section 3(1)(c)(i) of this Act by reason of the use as a slaughtering instrument, for the purpose of killing any deer, of a smooth-bore gun which—

(a)

is of not less gauge than 12 bore ;

(b)

has a barrel less than 24 inches (609.6 millimetres) in length ; and

(c)

is loaded with a cartridge purporting to contain shot none of which is less than .203 inches (5.16 millimetres) in diameter (that is to say, size AAA or any larger size).”