An Act Requiring Serial Numbers on Firearms and Prohibiting Undetectable Firearms

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STATE OF MAINE
_____
IN THE YEAR OF OUR LORD
TWO THOUSAND TWENTY-FIVE
_____
H.P. 745 - L.D. 1126
An Act Requiring Serial Numbers on Firearms and Prohibiting Undetectable
Firearms
Be it enacted by the People of the State of Maine as follows:
Sec. 1. 17-A MRSA §1060 is enacted to read:
§1060. 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), and that is constructed of 3.7 ounces of material
type 17-4 PH stainless steel in a shape resembling a handgun, as defined in 18 United States
Code, Section 921(a)(30).
2. Undetectable firearms prohibited. A person may not:
A. Manufacture or cause to be manufactured within this State, import into this State or
offer or expose for sale, sell or transfer an undetectable firearm; or
B. Intentionally or 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 or exposes for sale, sells or transfers an
undetectable firearm commits a Class C crime.
B. A person who intentionally or knowingly possesses an undetectable firearm
commits a Class D crime.
Sec. 2. 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. 3. 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
LAW WITHOUT
GOVERNOR'S
SIGNATURE

JANUARY 11, 2026
CHAPTER
537
PUBLIC LAW
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Sec. 4. 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. 5. 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. 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,
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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. Intentionally or knowingly possess one or more unfinished frames or receivers
unless each unfinished frame or receiver has been imprinted with a serial number by a
federal firearms licensee pursuant to federal law or section 2039;
B. Intentionally or 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. Intentionally or knowingly 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. Intentionally or knowingly possess one or more firearms or frames or receivers that
are not each imprinted with a serial number by a federal firearms licensee pursuant to
federal law or section 2039;
E. Intentionally or 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. Intentionally or knowingly 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
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(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 curio or relic, as defined in 27 Code of Federal Regulations, Section 478.11,
as in effect on November 19, 2019;
(7) A firearm that has been rendered permanently inoperable; or
(8) A firearm that was manufactured before 1968.
§2038. Violations
Beginning January 1, 2027, 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 for which a fine of not more than $50
may be adjudged;
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.
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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. Failure to make or retain records; violation. A person who violates subsection
1, paragraph D:
A. For a first offense, commits a civil violation for which a fine of not more than $250
may be adjudged;
B. For a 2nd offense, commits a civil violation for which a fine of not more than $500
may be adjudged; and
C. For a 3rd or subsequent offense, commits a Class E 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
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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.