The tricky wording in these sections are traps for the unwary:
I. “Commercial sale” means a sale, transfer, or exchange of a firearm that takes place at, or on the curtilage of, a firearm or "gun" show or pursuant to an offer to sell, buy, transfer, or exchange a firearm that took place at a gun show, or pursuant to an advertisement, posting, listing, or display.
And:
159-E:3 Exception. This chapter shall not apply to a noncommercial, private sale, transfer, or exchange of a firearm between individuals, provided neither party to the transaction is a prohibited person. If the status of either party’s eligibility to own or possess a firearm cannot be ascertained, the transaction shall be completed through a licensed firearm dealer pursuant to RSA 159-E:2, II.
159-E:4 Penalties.
I. Any individual or person who violates any provision of this chapter shall be guilty of a class B misdemeanor for a first offense, and a class A misdemeanor for a second or subsequent offense.