An Act Requiring Serial Numbers on Firearms and Prohibiting
Maine Legislature, Session 132, LD 1126
Committee: Criminal Justice and Public Safety
Sponsors: ZAGER, DAUGHTRY, FECTEAU
Amends: 25 MRSA §2016, 25 MRSA §2017

Legislative Document
No. 1126
H.P. 745
House of Representatives, March 18, 2025
An Act Requiring Serial Numbers on Firearms and Prohibiting 
Undetectable Firearms
Reference to the Committee on Criminal Justice and Public Safety suggested and ordered 
printed.
ROBERT B. HUNT
Clerk
Presented by Representative ZAGER of Portland.
Cosponsored by President DAUGHTRY of Cumberland and
Representative: Speaker FECTEAU of Biddeford, Senators: CYRWAY of Kennebec, 
TALBOT ROSS of Cumberland.
Be it enacted by the People of the State of Maine as follows:
Sec. 1.  25 MRSA §2016, sub-§1, ¶C, as enacted by PL 2023, c. 678, §1 and 
reallocated by RR 2023, c. 2, Pt. A, §40, is amended to read:
C.  "Firearm" has the same meaning as in Title 17‑A, section 2, subsection 12‑A and 
also includes an unfinished frame or receiver as defined in section 2036, subsection 10.
Sec. 2.  25 MRSA §2016, sub-§4, ¶B, as enacted by PL 2023, c. 678, §1 and 
reallocated by RR 2023, c. 2, Pt. A, §40, is amended to read:
B.  The sale of a firearm to a firearm dealer; or
Sec. 3.  25 MRSA §2016, sub-§4, ¶C, as enacted by PL 2023, c. 678, §1 and 
reallocated by RR 2023, c. 2, Pt. A, §40, is amended by amending subparagraph (3) to read:
(3)  A background check is not required under federal or state law.; or
Sec. 4.  25 MRSA §2016, sub-§4, ¶D is enacted to read:
D.  The return of a firearm or frame or receiver, as defined in section 2036, subsection 
8, to a person by a firearm dealer after the dealer has imprinted a serial number on the 
firearm or frame or receiver pursuant to federal law or section 2039 if the dealer returns 
the firearm or frame or receiver to the same person from whom the firearm or frame or 
receiver was received.
Sec. 5.  25 MRSA §2017 is enacted to read:
§2017.  Undetectable firearms prohibited
1.  Definition.  As used in this section, "undetectable firearm" means a firearm that can 
operate while in a form that is not as detectable as a security exemplar, as defined in 18 
United States Code, Section 922(p)(2)(C).
2.  Undetectable firearms prohibited.  A person may not:
A. Manufacture or cause to be manufactured within this State, import into this State or 
offer, expose for sale, sell or transfer an undetectable firearm; or
B. Knowingly possess an undetectable firearm;
3.  Violations.  The following penalties apply to violations of this section.
A.  A person who manufactures or causes to be manufactured within this State, who 
imports into this State or who offers, exposes for sale, sells or transfers an undetectable 
firearm commits a Class C crime.
B.  A person who knowingly possesses an undetectable firearm commits a Class D 
crime.
C.  A person commits a Class C crime if that person:
(1)  Knowingly possesses an undetectable firearm in a courthouse, on school 
property where the possession of a firearm is prohibited pursuant to Title 20-A, 
section 6552, in a voting place as defined in Title 21-A, section 1, subsection 49 or 
in a place where municipal, county or state business is conducted; or
(2)  Possesses an undetectable firearm with the intent to bring that firearm into a 
courthouse, onto school property where the possession of a firearm is prohibited 
pursuant to Title 20-A, section 6552, into a voting place as defined in Title 21-A, 
section 1, subsection 49 or into a place where municipal, county or state business 
is conducted.
D.  A person who uses an undetectable firearm while committing a Class A or Class B 
crime or while committing reckless conduct under Title 17-A, section 211 commits a 
Class C crime.
Sec. 6.  25 MRSA c. 253-A is enacted to read:
CHAPTER 253-A
FIREARMS WITHOUT SERIAL NUMBERS
§2036.  Definitions  
As used in this chapter, unless the context otherwise indicates, the following terms 
have the following meanings. 
1.  Computer numerical control milling machine.  "Computer numerical control 
milling machine" means a manufacturing device that cuts or shapes material into a specified 
shape as directed by computer code.
2.  Federal firearms licensee.  "Federal firearms licensee" means a federally licensed 
firearms dealer, federally licensed firearms importer or federally licensed firearms 
manufacturer.
3.  Federally licensed firearms dealer.  "Federally licensed firearms dealer" has the 
same meaning as in Title 15, section 395, subsection 1, paragraph E.
4.  Federally licensed firearms importer.  "Federally licensed firearms importer" 
means a licensed importer as defined in 18 United States Code, Section 921(a)(9).
5.  Federally licensed firearms manufacturer.  "Federally licensed firearms 
manufacturer" means a licensed manufacturer as defined in 18 United States Code, Section  
921(a)(10).
6.  Firearm.  "Firearm" has the same meaning as in Title 17‑A, section 2, subsection 
12‑A and also includes an unfinished frame or receiver.
7.  Fire control component.  "Fire control component" means a component necessary 
for a firearm to initiate, complete or continue a firing sequence, including a hammer, bolt, 
bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker or slide rails.
8.  Frame or receiver.  "Frame or receiver" means a part of a firearm that, when the 
complete firearm is assembled, provides housing or a structure designed to hold or integrate 
one or more fire control components, even if pins or other attachments are required to 
connect the fire control components. Any part of a firearm imprinted with a serial number 
is presumed to be a frame or receiver unless the United States Department of Justice, 
Bureau of Alcohol, Tobacco, Firearms and Explosives makes an official determination 
otherwise or there is other reliable evidence to the contrary.
9.  Three-dimensional printer.  "Three-dimensional printer" means a computer-aided 
manufacturing device capable of producing a 3-dimensional object from a 3-dimensional 
digital model through an additive manufacturing process that involves the layering of cross 
sections formed of a resin or similar material that are fused together to form a 3-
dimensional object.
10.  Unfinished frame or receiver.  "Unfinished frame or receiver" means any forging, 
casting, printing, extrusion, machined body or similar article that has reached a stage in 
manufacture when it may readily be completed, assembled or converted to be used as the 
frame or receiver of a functional firearm or that is marketed or sold to the public to become 
or be used as the frame or receiver of a functional firearm once completed, assembled or 
converted.
§2037.  Prohibited conduct  
1.  Prohibited conduct.  A person may not:
A.  Knowingly possess an unfinished frame or receiver unless the unfinished frame or 
receiver has been imprinted with a serial number by a federal firearms licensee pursuant 
to federal law or section 2039; 
B.  Knowingly import into this State, transfer or offer to transfer an unfinished frame 
or receiver unless the unfinished frame or receiver has been imprinted with a serial 
number by a federal firearms licensee pursuant to federal law or section 2039; 
C.  Purchase an unfinished frame or receiver imprinted with a serial number without 
undergoing a background check pursuant to 18 United States Code, Section 922(t) or 
Title 15, section 395;  
D.  Knowingly possess a firearm or frame or receiver that is not imprinted with a serial 
number by a federal firearms licensee pursuant to federal law or section 2039; 
E.  Knowingly import into this State, transfer or offer to transfer a firearm or frame or 
receiver that is not imprinted with a serial number by a federal firearms licensee 
pursuant to federal law or section 2039; or
F.  Purchase a frame or receiver imprinted with a serial number without undergoing a 
background check pursuant to 18 United States Code, Section 922(t) or Title 15, section 
395.
2.  Exceptions.  The following are exceptions to the provisions of subsection 1.
A.  Subsection 1, paragraphs A and B do not apply to:
(1)  A federal firearms licensee acting within the scope of the licensee's license;
(2)  An unfinished frame or receiver possessed by or transferred to a law 
enforcement officer for legitimate law enforcement purposes;
(3)  The transfer of an unfinished frame or receiver for the purpose of having the 
unfinished frame or receiver imprinted with a serial number pursuant to federal law 
or section 2039; or
(4)  A person who:
(a)  Is in possession of an unfinished frame or receiver that has been without a 
serial number for no more than 48 hours; and
(b)  Has an appointment with a federal firearms licensee pursuant to section 
2039, subsection 1, paragraph C to have the unfinished frame or receiver 
imprinted with a serial number.
B.  Subsection 1, paragraphs D and E do not apply to:
(1)  A federal firearms licensee acting within the scope of the licensee's license;
(2)  A firearm or frame or receiver without a serial number possessed by or 
transferred to a law enforcement officer for legitimate law enforcement purposes;
(3)  The transfer of a firearm or frame or receiver for the purpose of having the 
firearm or frame or receiver imprinted with a serial number pursuant to federal law 
or section 2039;
(4)  A person who:
(a)  Is in possession of a firearm or frame or receiver that has been without a 
serial number for no more than 48 hours; and
(b)  Has an appointment with a federal firearms licensee pursuant to section 
2039, subsection 1, paragraph C to have the firearm or frame or receiver 
imprinted with a serial number;
(5)  An antique firearm as defined in Title 15, section 394, subsection 1, paragraph 
A;
(6)  A firearm that has been rendered permanently inoperable; or 
(7)  A firearm that was manufactured before 1968.
§2038.  Violations  
Beginning October 1, 2026, the following provisions apply to violations of this chapter.
1.  Unlawful possession.  A person who violates section 2037, subsection 1, paragraph 
A or D:
A.  For a first offense, commits a civil violation and may be assessed a penalty of not 
more than $50;
B.  For a 2nd offense, commits a Class D crime; and
C.  For a 3rd or subsequent offense, commits a Class C crime.
2.  Unlawful importation, transfer, offer to transfer or purchase.  A person who 
violates section 2037, subsection 1, paragraph B, C, E or F:
A.  For a first offense, commits a Class D crime; and
B.  For a 2nd or subsequent offense, commits a Class C crime.
3.  Unlawful use.  A person who uses a firearm without a serial number while 
committing a Class A or Class B crime or while committing reckless conduct under Title 
17-A, section 211 commits a Class C crime.
§2039. Serial number imprinted; federal firearms licensees
1.  Federal firearms licensees.  A federal firearms licensee:
A.  May imprint a serial number on a firearm or frame or receiver without a serial 
number pursuant to this section;
B.  May schedule an appointment with a person to imprint a serial number on a firearm 
or frame or receiver without a serial number pursuant to this section;
C.  Who schedules an appointment with a person to imprint a serial number on a  
firearm or frame or receiver without a serial number pursuant to this section shall, at 
the time the appointment is scheduled:
(1)  Make a record of the appointment, which must be retained by the federal 
firearms licensee for no less than 30 days; and
(2)  Provide the person with whom the appointment is scheduled with a physical 
or digital record confirming that appointment; 
D.  Who imprints a serial number on a firearm or frame or receiver pursuant to this 
section shall make and retain records of the imprinting that comply with the 
requirements under federal law for the sale of a firearm. In addition to any record 
required by federal law, the record must include the date of the imprinting; name, age 
and residence of any person to whom the firearm or frame or receiver is transferred; 
and the serial number imprinted on the firearm or frame or receiver; and
E.  May not be deemed a firearms manufacturer solely for imprinting a serial number 
on a firearm or frame or receiver pursuant to this section.
2.  Violations.  A person who violates subsection 1:
A.  For a first offense, commits a civil violation and may be assessed a penalty of not 
more than $2,500; and
B.  For a 2nd or subsequent offense, commits a Class C crime.
3.  Serial number imprinted.  A serial number imprinted pursuant to this section must   
begin with the federal firearms licensee's abbreviated federal firearms license number, 
which is the first 3 and last 5 digits of the license number, and must be followed by a hyphen 
and then by a unique identification number. The serial number may not be duplicated on 
any other firearm or frame or receiver imprinted by the federal licensee and must be 
imprinted in a manner that complies with the requirements under 27 Code of Federal 
Regulations, Section 478.92 for imprinting serial numbers on firearms, including that the 
serial number be at the minimum size and depth and not susceptible to being readily 
obliterated, altered or removed.
4.  Returning firearm or frame or receiver imprinted with serial number.  
Returning a firearm or frame or receiver to a person after the firearm or frame or receiver 
has been imprinted with a serial number pursuant to federal law or this section constitutes 
a transfer that requires a background check of the transferee. A federal firearms licensee 
that imprints a serial number on a firearm or frame or receiver pursuant to this section shall 
conduct a background check on the transferee pursuant to 18 United States Code, Section 
922(t) or Title 15, section 395. If the transfer is denied pursuant to the background check, 
the federal firearms licensee shall deliver the firearm or frame or receiver to a law 
enforcement agency for disposition. The law enforcement agency shall provide the federal 
firearms licensee with a receipt on agency letterhead for the firearm or frame or receiver. 
5.  Manufacturers of frames or receivers.  A person who manufactures a frame or 
receiver, including by a 3-dimensional printer or computer numerical control milling 
machine, shall cause the frame or receiver to be imprinted with a serial number by a federal 
firearms licensee pursuant to federal law and this section.
6.  Exceptions for manufacturers of frames or receivers.  Subsection 4 does not 
apply to:
A.  A federally licensed firearms manufacturer acting within the scope of the 
manufacturer's license;
B.  The transfer of a frame or receiver for the purpose of having the frame or receiver 
imprinted with a serial number pursuant to federal law or this section; or
C.  A person who:
(1)  Is in possession of a frame or receiver that has been without a serial number 
for no more than 48 hours; and
(2)  Has an appointment with a federal firearms licensee to have the frame or 
receiver imprinted with a serial number pursuant to section 2039, subsection 1, 
paragraph C.
SUMMARY
This bill establishes unlawful conduct related to certain firearms and firearm 
components without serial numbers. The bill also establishes penalties for violations of the 
provisions. The bill also establishes requirements for the imprinting of certain firearms and 
firearm components with serial numbers by federal firearms licensees and prohibits the 
manufacture, possession, importation, offer, sale or transfer of undetectable firearms in the 
State.