Quick Answer: Massachusetts General Laws Chapter 140, Section 131L makes it unlawful to store or keep any firearm, rifle, or shotgun unless it’s locked in a container or disabled by a tamper-resistant lock or safety device — with no exception for whether a minor lives in the home, unlike most states’ child-access laws. Penalties range from $1,000-$7,500 and up to 1.5 years for a basic violation up to $10,000-$20,000 and 4-15 years if a large-capacity weapon is left accessible to a minor without a valid Firearm Identification (FID) card. Unlike California’s SB 53, Massachusetts doesn’t require a device from a state-certified roster — any safe with a functioning lock satisfies the rule.
Massachusetts runs one of the broadest firearm-storage mandates in the country, and it’s easy to misunderstand because most national coverage of “gun safe laws” focuses on California. This guide breaks down what §131L actually requires, how its penalty tiers work, and why a Massachusetts gun owner doesn’t need to chase a certified-product list the way a California resident does.
What §131L actually requires
Under MGL c.140 §131L, it is unlawful to store or keep any firearm, rifle, or shotgun unless it is:
- Secured in a locked container, or
- Equipped with a tamper-resistant mechanical lock or other safety device, engaged so that the weapon cannot be operated by anyone other than the owner or another lawfully authorized user.
The law also separately covers stun guns, which must be kept in a locked container accessible only to the owner or a lawful user. The only exception to the entire storage requirement: a weapon is not considered “stored or kept” while it’s being carried by, or is under the direct control of, the owner or another lawfully authorized user. Set it down unattended, and the clock starts — there’s no grace period defined by room, lock status of the house, or whether anyone else is home.
| Violation | Fine | Prison |
|---|---|---|
| Standard firearm, rifle, or shotgun (not large-capacity), stored unlocked | $1,000 – $7,500 | Up to 1.5 years |
| Large-capacity weapon or machine gun, stored unlocked | $2,000 – $15,000 | Up to 12 years |
| Rifle/shotgun (not large-capacity) accessible to a minor without a valid FID card | $2,500 – $15,000 | 1.5 – 12 years |
| Large-capacity firearm/rifle/shotgun/machine gun accessible to a minor without a valid FID card | $10,000 – $20,000 | 4 – 15 years |
A violation of §131L is also treated as evidence of wanton or reckless conduct if a minor who wasn’t trespassing (or was a foreseeable trespasser) gains access to the weapon and someone is hurt or killed — a civil-liability exposure on top of the criminal fine, according to the statute’s own text (cross-referenced via Law of Self-Defense’s statute archive and Giffords Law Center’s state-law summary).
Liberty Centurion 18
- A locked RSC-rated safe like this satisfies §131L's functional test — no certified-device roster to check against, unlike California.
- The electronic lock engages automatically on close, meeting the "only the owner or authorized user can operate it" standard.
No certified-device roster — the biggest difference from California
California’s SB 53 ties legal compliance to a specific DOJ-maintained list: a locked safe that isn’t on the Firearm Safety Device roster doesn’t satisfy the law even though it’s genuinely locked (see our California gun safe law guide for that framework). Massachusetts works differently. §131L defines compliance functionally — a locked container, or a tamper-resistant lock/safety device engaged so an unauthorized person can’t operate the weapon — with no requirement that the specific product appear on a state-approved list.
Massachusetts does maintain a separate approved firearm safety device list under §131K, but that section governs a narrower situation: every firearm or large-capacity weapon sold in Massachusetts must come with a state-approved safety device (the seller doesn’t have to install it, just include it). That’s a point-of-sale rule about new transfers, not a model-by-model compliance test that applies to every safe already sitting in a Massachusetts home — a distinction worth knowing if you’ve seen California’s roster requirement and assumed every state works the same way.
Dealer warning requirements
Massachusetts also requires firearm dealers to post a warning at each purchase counter in bold type at least one inch tall, and to give buyers the same warning in writing in bold type at least a quarter-inch tall (MGL c.140 §123). Separately, under §131K, a handgun or large-capacity weapon sold without a safety device to prevent unauthorized discharge is treated as legally defective — selling one without it is a breach of warranty and an unfair trade practice.
Is a gun safe enough on its own?
For most buyers, yes. Because §131L’s test is functional rather than roster-based, a properly locked RSC-rated or UL-listed gun safe clears the bar as long as the lock is actually engaged when the firearm isn’t being carried. The practical risk isn’t picking the “wrong” safe — it’s leaving a locked safe open, or leaving a firearm out while running an errand down the hall, since the carry exception only covers direct control, not “I’ll be right back.” For buyers weighing a fast-access option that still satisfies the carry exception’s spirit, our best bedside gun safe guide covers safes designed to be opened and relocked in seconds rather than left ajar. And if fire protection matters alongside the legal minimum, our gun safe fire rating guide explains how to read a genuine UL or ETL rating instead of a marketing number.
The bottom line
Massachusetts requires every firearm, rifle, and shotgun to be locked up or disabled by an engaged safety device any time it isn’t in someone’s hands — a broader, simpler-to-satisfy rule than California’s roster-based system, but one with real teeth: penalties climb to $10,000-$20,000 and up to 15 years if a large-capacity weapon is left accessible to a minor. A properly closed Liberty Centurion or any other RSC-rated safe with the lock engaged satisfies §131L on its face — no certified-product list to cross-check, just a lock that actually works and is actually used. New York takes a third approach again — its New York gun safe law guide covers a storage duty that only attaches when a minor or a legally prohibited person lives in the household, rather than applying to every firearm owner the way Massachusetts does.
Sources: Mass. General Laws c.140 §131L, mass.gov; MA §131L firearms storage, Law of Self-Defense statute archive; Safe Storage in Massachusetts, Giffords Law Center.