Assault Style Firearms

MASSACHUSETTS ASSAULT-STYLE FIREARM WARNING

Massachusetts uses a broad statutory definition of "assault-style firearm."

A firearm may fall within the definition because of its configuration, features, model, receiver, internal components, or inclusion on a state roster.

Do not rely on appearance, caliber, magazine capacity, or the terminology used by a manufacturer alone.

Is My Firearm an Assault-Style Firearm?

Massachusetts Assault-Style Firearm Navigator

Answer the following questions for a starting-point explanation. This tool is designed to identify issues requiring further review. It does not replace a firearm-specific legal analysis.

1. How does the firearm operate? 2. What type of firearm is it? 3. Can it accept a detachable feeding device? 4. How many listed Massachusetts features does it have? 5. Is it an enumerated firearm, copy, duplicate, or potentially interchangeable with one? 6. When was it lawfully possessed in Massachusetts? 7. Is the firearm registered and serialized as required?

1. Massachusetts Definition

The Massachusetts definition of "assault-style firearm" is contained in M.G.L. c. 140, §121.

The definition includes several separate categories. A firearm may qualify under any one of them.

2. Semiautomatic Centerfire Rifles

A semiautomatic centerfire rifle capable of accepting a detachable feeding device is an assault-style firearm if it has at least two of the following features:

Folding or Telescopic Stock

Thumbhole Stock or Pistol Grip

Forward or Second Handgrip
Including a protruding grip that can be held by the non-trigger hand.

Threaded Barrel
Designed to accommodate a flash suppressor, muzzle brake, or similar feature.

Barrel Shroud
A shroud encircling all or part of the barrel to shield the bearer's hand from heat, excluding a slide enclosing the barrel.

3. Semiautomatic Pistols

A semiautomatic pistol capable of accepting a detachable feeding device is an assault-style firearm if it has at least two of the following:

a feeding device that attaches outside the pistol grip;
a second handgrip or protruding grip for the non-trigger hand;
a threaded barrel capable of accepting a flash suppressor, forward handgrip, or silencer; or
a barrel shroud designed to shield the bearer's hand from heat, excluding the slide.

4. Semiautomatic Shotguns

A semiautomatic shotgun is an assault-style firearm if it includes at least two of the following features:

folding or telescopic stock;
thumbhole stock or pistol grip;
protruding grip for the non-trigger hand; or
capacity to accept a detachable feeding device.

Statutory exclusion: A semiautomatic shotgun that cannot hold more than five rounds in a fixed or detachable feeding device is excluded from the assault-style firearm definition.

5. Enumerated Firearms

M.G.L. c. 140, §121 specifically identifies several firearm families as assault-style firearms, regardless of caliber.

Avtomat Kalashnikov / AK — all models;
Action Arms / Israeli Military Industries UZI and Galil;
Beretta AR70 / SC-70;
Colt AR-15;
FN/FAL, FN/LAR and FNC;
SWD M-10, M-11, M-11/9 and M-12;
Steyr AUG;
INTRATEC TEC-9, TEC-DC9 and TEC-22; and
revolving-cylinder shotguns, including the Street Sweeper and Striker 12.

The statute also includes certain copies or duplicates of enumerated firearms.

6. Copies and Duplicates

Massachusetts law defines a copy or duplicate using more than appearance.

The analysis can include whether the firearm:

was manufactured or subsequently configured to accept a detachable magazine;
has internal functional components substantially similar in construction and configuration to an enumerated firearm; or
has a receiver that is the same as or interchangeable with the receiver of an enumerated firearm.

July 20, 2016 provision: The statute states that a firearm will not be treated as a copy or duplicate of the firearms identified in the applicable enumerated/roster provisions if it was sold, owned, and registered before July 20, 2016.

7. Firearms Excluded From the Definition

M.G.L. c. 140, §121 specifically excludes several categories.

Manual Actions
Bolt, pump, lever, or slide-action firearms.

Permanently Inoperable Firearms
Firearms permanently rendered unable to qualify as semiautomatic assault-style firearms.

Certain Antiques / Relics / Props
Subject to the specific statutory requirements.

Federal Appendix A Firearms
Qualifying firearms identified in the historical federal Appendix A provision referenced by the Massachusetts statute.

Limited-Capacity Semiautomatic Shotguns
Semiautomatic shotguns unable to hold more than five rounds.

8. Possession Ban — M.G.L. c. 140, §131M

Massachusetts generally prohibits possessing, owning, offering for sale, selling, transferring, or importing an assault-style firearm.

The principal possession exception in §131M applies to an assault-style firearm that was:

lawfully possessed within Massachusetts on August 1, 2024;
possessed by an LTC holder or qualifying firearms-license holder;
registered as required by M.G.L. c. 140, §121B; and
serialized as required by M.G.L. c. 140, §121C.

An LTC alone does not authorize possession of every assault-style firearm.

M.G.L. c. 140, §131 expressly states that an LTC does not authorize possession, transfer, or carrying of an assault-style firearm unless permitted by §131M.

9. August 1, 2024 Is a Critical Date

AUGUST 1, 2024

Section 131M protects qualifying assault-style firearms that were lawfully possessed within Massachusetts on August 1, 2024, provided the statutory licensing, registration, and serialization requirements are satisfied.

A firearm acquired after August 1, 2024 should not be assumed to qualify simply because an identical model was lawfully owned before that date.

10. July 20, 2016 Is Also Important

JULY 20, 2016

The current statutory definition contains a separate protection for certain firearms that otherwise might be treated as a copy or duplicate of an enumerated firearm.

The statute says such a firearm will not be considered a copy or duplicate if it was:

sold before July 20, 2016;
owned before July 20, 2016; and
registered before July 20, 2016.

11. The 1994 Date

September 13, 1994 remains relevant to several parts of Massachusetts firearm law, particularly certain large-capacity feeding devices and historical assault-firearm classifications.

Do not confuse the dates:

September 13, 1994
July 20, 2016
August 1, 2024

Each can have a different legal significance.

12. Registration

An assault-style firearm relying on the possession exception in §131M must be registered as required by M.G.L. c. 140, §121B.

Registration is governed procedurally by 501 CMR 19.00.

Registration does not itself establish that a firearm qualifies for the §131M possession exception.

13. Serialization

Section 131M also requires qualifying grandfathered assault-style firearms to be serialized in accordance with M.G.L. c. 140, §121C.

Serialization procedures are contained in 501 CMR 20.00.

Registration and serialization are separate legal requirements.

14. Large-Capacity Classification

Under M.G.L. c. 140, §121, an assault-style firearm also falls within the statutory definition of a large-capacity firearm.

This means an assault-style firearm may be subject to multiple Massachusetts firearm classifications at the same time.

Magazine legality must also be analyzed separately.

15. Assault-Style Firearm Roster

M.G.L. c. 140, §131¾ requires the Secretary of Public Safety and Security, with advice from the Firearm Control Advisory Board, to publish a roster of assault-style firearms prohibited under §131M.

Current status — September 22, 2026: The Firearm Control Advisory Board is still publicly discussing the cover letter and submission process for the prohibited assault-style firearm roster. Check the current EOPSS / DCJIS roster page before relying on any draft roster.

16. GOAL Analysis

GOAL INFORMATION

GOAL describes Massachusetts assault-style firearm law as particularly complex because the definition in §121 must be read together with §131M, the enumerated-firearm provisions, copy-or-duplicate rules, feature tests, registration, serialization, and developing state roster interpretations.

GOAL has also cautioned that some interpretations currently being advanced by the Commonwealth may differ from GOAL's reading of the law.

Where GOAL disagrees with or questions a Commonwealth interpretation, that material should be identified as GOAL legal analysis, not presented as statutory text.

17. GOAL's Current State-Interpretation Warning

GOAL currently reports that the Commonwealth is taking a very restrictive view of the law, including questions concerning:

enumerated firearms;
copies and duplicates;
the July 20, 2016 date;
the August 1, 2024 date;
feature changes made after acquisition;
frames and receivers;
registration;
serialization; and
the proposed assault-style firearm roster.

Because these issues may involve disputed interpretations, owners should review the latest GOAL and Commonwealth guidance before making changes to a firearm or transferring it.

18. Do Not Modify Without Checking First

Adding or changing parts can affect firearm classification.

Before adding a:

folding or telescopic stock;
pistol grip;
thumbhole stock;
forward grip;
threaded barrel;
barrel shroud; or
detachable-magazine configuration,

review the Massachusetts assault-style firearm definition.

A configuration change can create a different legal analysis even if the underlying receiver has not changed.

Assault-Style Firearm Checklist

1. Identify the Action
Manual action or semiautomatic?

2. Identify the Type
Rifle, pistol, shotgun, frame, or receiver.

3. Count the Features
Compare the firearm against the exact §121 feature list.

4. Check the Enumerated List
Determine whether the model or firearm family is specifically named.

5. Check Copy / Duplicate Status
Internal components and receiver interchangeability may matter.

6. Determine Critical Dates
1994, July 20, 2016, and August 1, 2024 may each matter.

7. Check Registration
Review §121B and 501 CMR 19.

8. Check Serialization
Review §121C and 501 CMR 20.

9. Check the State Roster
Review the current EOPSS / FCAB assault-style firearm roster when officially published.

10. Check GOAL Updates
Review current GOAL analysis before modifying, transferring, or acquiring the firearm.

Primary Sources

M.G.L. c. 140, §121 — definition of assault-style firearm.
M.G.L. c. 140, §131M — possession, ownership, sale, transfer, importation, and statutory exceptions.
M.G.L. c. 140, §131¾ — assault-style firearm roster.
M.G.L. c. 140, §131 — License to Carry.
Massachusetts Approved Firearms Rosters
GOAL — Assault Style Firearms
GOAL — Chapter 135 Definitions
GOAL — Chapter 135 Breakdown

Last reviewed: September 22, 2026.

Massachusetts assault-style firearm law remains complex, and state roster implementation is still developing. Check the current statute, EOPSS / DCJIS information, and GOAL analysis before relying on this page for a specific firearm.