Mass. Gen. Laws ch. 140 § 131O
Notwithstanding any general or special law, rule or regulation to the contrary, the colonel of state police, in conjunction with the secretary of the executive office of public safety, shall promulgate rules and regulations implementing a statewide firearms surrender program. In conjunction with this program only, any citizen of the commonwealth who complies with the policies set forth by the colonel shall not be asked for identification and shall be immune from prosecution for possession of such firearm; provided, however, that nothing herein shall prohibit the prosecution of any person for the unlawful possession of a firearm who is not in compliance with the conditions and procedures established by the colonel; and provided further, that nothing herein shall prohibit the prosecution of any person for any other offense committed within the commonwealth.
Any firearm surrendered in accordance with the provisions of this program that is reported stolen shall be returned to its lawful owner; provided, however, that any firearm suspected to be evidence in a crime shall remain in the custody and control of the department of state police in the same manner as any other such firearm lawfully seized by the department of state police. The department of state police may test-fire and preserve any and all firearms voluntarily surrendered. All firearms that have been voluntarily surrendered that are not suspected to be evidence of criminal activity and have not been reported stolen shall be disposed of in accordance with procedures established by the colonel.
Mass. Gen. Laws ch. 140, § 140:131O