Per RSA 627:4

II. A person is justified in using deadly force upon another person when he reasonably believes that such other person:
(a) Is about to use unlawful, deadly force against the actor or a third person;
(b) Is likely to use any unlawful force against a person present while committing or attempting to commit a burglary;
(c) Is committing or about to commit kidnapping or a forcible sex offense; or
(d) Is likely to use any unlawful force in the commission of a felony against the actor within such actor's dwelling or its curtilage.
II-a. A person who responds to a threat which would be considered by a reasonable person as likely to cause serious bodily injury or death to the person or to another by displaying a firearm or other means of self-defense with the intent to warn away the person making the threat shall not have committed a criminal act.

It is also worth noting that there is no duty to retreat in NH.

George


�Out of every one hundred men, ten shouldn't even be there, eighty are just targets, nine are the real fighters, and we are lucky to have them, for they make the battle. Ah, but the one, one is a warrior, and he will bring the others back.�