Chapter 141 Section 131L Makes it unlawful to store or keep any firearm, rifle or shotgun including, but not limited to, large capacity weapons, or machine gun in any place unless such weapon is secured in a locked container or equipped with a tamper-resistant mechanical lock or other safety device, properly engaged so as to render such weapon inoperable by any person other than the owner or other lawfully authorized.

Other locks apply, this law does not specify trigger, or approved locks.