Here, from the Criminal Code of Canada Section 34, is the self-defense provision in view:
34 (1) A person is not guilty of an offence if
(a) they believe on reasonable grounds that force is being used against them or another person or that a threat of force is being made against them or another person;
(b) the act that constitutes the offence is committed for the purpose of defending or protecting themselves or the other person from that use or threat of force; and
(c) the act committed is reasonable in the circumstances.
这里虽然没有明确说“你可以用枪”,但是你看(c),只要你的行为符合当时的条件就可以。如果对方已经要杀人了,你最合适的反应是什么?肯定不是挥拳吧。