March 24, 2023
Gun Control: ATF Final “Stabilizing Brace” Rule
On January 31, 2023, the Bureau of Alcohol, Tobacco,
Today, ATF’s Firearms and Ammunition Technology
Firearms and Explosives (ATF) issued a final rule entitled
Division (FATD) is the principal federal authority charged
“Factoring Criteria for Firearms Attached with ‘Stabilizing
with classifying firearms and ammunition under federal
Braces.”’ The rule redefines the term “rifle” as a means to
law. The FATD is also responsible for processing requests
reclassify certain brace-equipped firearms as short-barreled
for importation and domestic manufacturing evaluations,
rifles (SBRs). The firearms in question were previously
and requests for marking variances. Upon written request,
classified as pistols and, as such, were regulated solely
the FATB also issues determination (classification) letters
under the Gun Control Act of 1968 (GCA). Reclassified as
regarding technical aspects of the NFA, GCA, and other
SBRs, these firearms now fall under the more restrictive
applicable federal laws. Classification letters, once released
1934 National Firearms Act (NFA). Under the rule,
to the original requestor, are not made available to the
moreover, nearly all rifled-bore firearms with barrels less
public, though they may be obtained by outside interested
than 16 inches and equipped with braces or similar devices
parties pursuant to the Freedom of Information Act (FOIA)
appear to be non-transferable until registered with the
and Privacy Act of 1974. The letters released are often
Attorney General under the NFA.
redacted to protect proprietary information and the privacy
of individuals. In some cases, the letters are released to
To comply with the rule, federal firearms licensees (FFLs)
other parties by the original requesters.
and private owners of these firearms have several options.
They may submit an NFA tax/registration form and other
ATF has compiled firearms-related statutes and regulations
required documentation (e.g., fingerprints and personal
in a Federal Firearms Regulations Reference Guide, 2014
photo) to ATF by May 31, 2023 on the firearms in question.
that includes some, but not all rulings. More recent rulings
No tax payment is required, as ATF has opted to “forbear”
are periodically published on ATF's website (www.atf.gov).
the $200 NFA tax. Alternatively, possessors may alter the
Nevertheless, there is no central index of ATF letter rulings,
firearms by permanently removing the brace or by replacing
determinations (however redacted), or open letters. Hence,
the barrel with one longer than 16 inches. They may also
observers caution that there is no certainty that any
destroy or turn the firearms over to the authorities as
individual who files a FOIA request for previously issued
contraband. Some Members of Congress have introduced
classification letters will receive every relevant letter issued
legislation to nullify the ATF rule by removing all short-
by the ATF. In addition, some observers maintain that some
barreled firearms, as well as similar firearms, from the
ATF rulings have been inconsistent with previous rulings,
purview of the NFA. See H.R. 381, H.R. 646/S. 163, S.
though these possible inconsistencies might reflect changed
361, H.J. Res. 44, and H.R. 1678.
legal reasoning by DOJ and ATF attorneys.
ATF and Firearm Classifications
GCA-NFA Firearm Definitions
Under the Attorney General’s delegated authority, ATF
Under the GCA-NFA construct, NFA-regulated firearms
promulgates regulations and guidance pursuant to the GCA
are regulated first under the GCA. The three basic types of
and NFA. ATF issues firearm classifications in letter
firearms defined under the GCA are shotguns, rifles, and
rulings and open letters, as well as other written private
handguns. Congress included identical statutory definitions
determinations, to assist FFLs and others in complying with
for the terms “shotgun” and “rifle” in the GCA and NFA.
their responsibilities under federal law. Although these
forms of guidance do not have the force of law, they
The term “shotgun” means “a weapon designed or
represent ATF’s best interpretation of statute and reported
redesigned, made or remade, and intended to be
case law, and are relied upon as precedent in court cases.
fired from the shoulder and designed or redesigned
ATF determinations are subject to the Administrative
and made or remade to use the energy of an
Procedure Act (APA) and can be challenged in federal
explosive to fire through a smooth bore either a
court after all other administrative remedies have been
number of ball shot or a single projectile for each
exhausted. These forms of guidance (ruling, open, and
single pull of the trigger” (18 U.S.C. §921(a)(5) and
private determination letters) are arguably artifacts of
26 U.S.C. §5845(d)).
ATF’s origins in the Department of the Treasury, before
Congress transferred ATF from Treasury to the Department
The term “rifle” means “a weapon designed or
of Justice (DOJ) in 2003. While the GCA is criminal law,
redesigned, made or remade, and intended to be
firearms and ammunition are regulated under federal statute
fired from the shoulder and designed or redesigned
primarily as commodities. These guidance documents
and made or remade to use the energy of an
arguably allow ATF to more quickly and efficiently address
explosive to fire only a single projectile through a
emerging developments than by promulgating a regulation
rifled bore for each single pull of the trigger” (18
under the APA.
U.S.C. §921(a)(7) and 26 U.S.C. §5845(c)).
https://crsreports.congress.gov

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Gun Control: ATF Final “Stabilizing Brace” Rule
It follows that the defining feature of a long gun (shotgun or
Relatedly, some GCA-regulated handguns and pistol grip
rifle) is a shoulder stock. Unlike “smoothbore” shotguns,
firearms are dimensionally equivalent—in terms of their
the barrel bores of rifles are machine-cut with spiraling
barrel lengths, overall lengths, and/or barrel bores—to other
lands and grooves that impart a flight-stabilizing spin on a
NFA-regulated firearms. It is a felony to modify an existing
bullet around its axis of trajectory. Rifled-bore handguns
rifle or shotgun by shortening its stock and/or barrel(s) into
are regulated under the GCA.
a short-barreled rifle or shotgun without following NFA
requirements, which includes remitting a $200 making tax.
The term “handgun” means “(A) a firearm which
However, a handgun with equivalent dimensions does not
has a short stock and is designed to be held and fired
trigger the NFA requirements or prohibitions, as long as a
by the use of a single hand; and (B) any
shoulder stock is never affixed to its frame or receiver.
combination of parts from which a firearm
described in subparagraph (A) can be assembled”
Stabilizing Brace or Shoulder Stock
(18 U.S.C. §921(a)(29)).
ATF had long ruled that the attachment of a shoulder stock
to a handgun or pistol grip firearm transformed that solely
It follows that the defining feature of a handgun is its short
GCA-regulated firearm into an NFA-regulated short-
stock. The term handgun includes both pistols and revolvers
barreled rifle or shotgun. In November 2012, however, ATF
(26 C.F.R. §§478.11 and 479.11). The GCA places no
ruled that attaching a stabilizing brace to an Armalite (AR)-
restrictions on the barrel or overall length of such handguns,
type pistol would not change that firearm's classification
except their design allows them to be used singlehandedly.
from a solely GCA-regulated handgun to an NFA-regulated
SBR. As brace-equipped firearms became popular, it
The NFA further regulates machine guns, silencers,
became clear that many people intended to use stabilizing
“sawed-off” shotguns, and other weapons considered to be
braces as quasi-shoulder stocks, instead of strapping the
more dangerous and unusual than firearms typically owned
brace to their forearm. In response, ATF issued guidance
by civilians in the 1930s. These weapons were sometimes
that appeared to some to be contradictory to previous
used by interstate bank robbers, bootlegging gangsters, and
guidance. Under the final 2023 rule, ATF has revised its
other criminals, who on occasion outgunned federal agents
definition of the term “rifle” to capture rifled-bore firearms,
and the police. Pertaining to the ATF final rule, the NFA
equipped with a “stabilizing brace” or similar device that
regulates short-barreled shotguns (SBSs) and short-barreled
provides sufficient surface area to allow the firearm to be
rifles (SBRs):
shoulder-fired, in consideration of the following factors:
(1) shotguns with barrels less than 18 inches in
length and weight consistent with other rifles;
length, (2) rifles with barrels less than 16 inches in
length, or (3) any existing shotgun or rifle that has
length of pull from the center of the trigger to the
been modified to be less than 26 inches in overall
center of the shoulder stock, or similar attachment
length by shortening its stock and/or barrel(s). (See
that is consistent with other rifles;
18 U.S.C. §§921(a)(6) and (8), and 26 U.S.C.
lights and scopes that the design and use of would
§5845(a).)
normally require the firearm to be shouldered;
Also pertaining to the rule, the NFA regulates “any other
any component or rearward portion of a receiver
weapons” (AOWs) and “destructive devices” (DDs).
that provides sufficient surface area to allow (1) the
AOWs include certain deceptive or disguised firearms (e.g.,
firearm to be shoulder-fired or (2) the attachment of
umbrella, belt buckle, and pen guns). The AOW
a device that would provide such surface area; and
classification also captures smoothbore handguns (less than
26 inches in overall length) and other “concealable”
a manufacturer’s direct or indirect marketing and
firearms with combination smoothbore and rifled bore
promotional material indicating the firearm could
barrels between 12 and 18 inches in length (26 U.S.C.
be shoulder-fired.
§5845(e)). DDs include any arms with barrel bore
diameters greater than one-half inch (e.g., grenade
Notably, the final rule does not address brace-equipped,
launchers, bazookas, mortars, and certain “non-sporting”
smoothbore pistol grip firearms, though the text preceding
shotguns); as well as certain munitions and incendiaries
the actual rule has led some readers to question whether
(e.g., grenades, rockets, mortar rounds, mines, and Molotov
such firearms should be submitted for re-classification.
cocktails) ((18 U.S.C. §921(a)(4) and 26 U.S.C. §5845(f)).
However, ATF has stated that this is not so. Nonetheless,
this rule will effect several million individuals who have
There is a fourth type of firearm—undefined in statute or
purchased or assembled brace-equipped firearms. Critics
regulation—that is regulated solely under the GCA. Since
contend that ATF has exceeded its authority, placing lawful
at least 1976, ATF adopted 26 inches in overall length as
gun owners in legal jeopardy, while not addressing the root
the determining dimension that separates NFA-regulated
causes of gun violence. Supporters point to four mass
“concealable” smoothbore handguns, or AOWs, from solely
public shootings involving assailants who used braced
GCA-regulated short-stocked, smoothbore firearms. ATF
firearms and view the rule as within ATF’s delegated
adopted this presumptive dimension of concealability from
authority and in the interests of public safety.
the statutory definitions for SBRs and SBSs discussed
above. ATF sometimes refers to these GCA-regulated
William J. Krouse, Specialist in Domestic Security and
short-stocked, smoothbore firearms, which are greater than
Crime Policy
26 inches in overall length, as “pistol grip firearms.”
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Gun Control: ATF Final “Stabilizing Brace” Rule

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