Massachusetts General Laws Part I. Administration of the Government (Ch. 1-182) Ch. 140, § 131C

(a) No person carrying a loaded firearm under a license issued pursuant to section 129B131 or 131F or through an exemption under section 129C shall carry the loaded firearm in a vehicle unless the loaded firearm while carried in the vehicle is under the direct control of the person. Whoever violates this subsection shall be punished by a fine of $500.

(b) No person possessing a large capacity rifle or shotgun under a license issued pursuant to section 131 or 131F or through an exemption under section 129C shall possess the large capacity firearm in a vehicle unless the large capacity firearm is unloaded and secured in a locked container as defined in section 121. Whoever violates this subsection shall be punished by a fine of not less than $500 nor more than $5,000.

(c) This section shall not apply to: (i) an officer, agent or employee of the commonwealth, any state or the United States; (ii) a member of the military or other service of any state or of the United States; (iii) a duly authorized law enforcement officer, agent or employee of a municipality of the commonwealth; provided, however, that a person described in clauses (i) to (iii), inclusive, is authorized by a competent authority to carry or possess the firearm so carried or possessed and is acting within the scope of the person's official duties.

(d) A conviction of a violation of this section shall be reported immediately by the court or magistrate to the licensing authority. The licensing authority shall immediately revoke the firearm identification card or license of the person convicted of a violation of this section. No new firearm identification card or license may be issued to a person convicted of a violation of this section until 1 year after the date of revocation of the firearm identification card or license.