New Hampshire has a preemption clause in state law, I believe.
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Yuup
http://www.gencourt.state.nh.us/rsa/html/xii/159/159-26.htm
[h=1]TITLE XII
PUBLIC SAFETY AND WELFARE[/h][h=2]CHAPTER 159
PISTOLS AND REVOLVERS[/h][h=2]State Jurisdiction[/h][h=3]Section 159:26[/h] 159:26 Firearms, Ammunition, and Knives; Authority of the State. –
I. To the extent consistent with federal law, the state of New Hampshire shall have authority and jurisdiction over the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearms components, ammunition, firearms supplies, or knives in the state. Except as otherwise specifically provided by statute, no ordinance or regulation of a political subdivision may regulate the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearms components, ammunition, or firearms supplies in the state. Nothing in this section shall be construed as affecting a political subdivision's right to adopt zoning ordinances for the purpose of regulating firearms or knives businesses in the same manner as other businesses or to take any action allowed under RSA 207:59.
II. Upon the effective date of this section, all municipal ordinances and regulations not authorized under paragraph I relative to the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearm components, ammunition, firearms supplies, or knives shall be null and void.Source. 2003, 283:2. 2011, 139:1, eff. Aug. 6, 2011.