When I asked the local cops about shooting at night for the purpose of training with night sights and or flashlights they said not to shoot after 10:00pm which is when quiet hours are in effect.
The New Hampshire law dealing with disruptive noise is RSA 644:2, III(a), which states:
644:2 Disorderly Conduct. – A person is guilty of disorderly conduct if:
III. He purposely causes a breach of the peace, public inconvenience, annoyance or alarm, or recklessly creates a risk thereof, by:
(a) Making loud or unreasonable noises in a public place, or making loud or unreasonable noises in a private place which can be heard in a public place or other private places, which noises would disturb a person of average sensibilities;
I've got a word document by Michael Pelletier called Noise and Firearms Regulation in New Hampshire dated August 22, 2005. If you'd like I can post the whole thing.