The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) issued a slew of new and proposed rules today. One of these is the rule titled “Revising Machine Gun Definition in Response to Supreme Court Decision” (FR Document: 2026-08926). The rule is scheduled for publication in the Federal Register on May 6, 2026, and becomes effective on that date.
The rule responds to the U.S. Supreme Court’s June 14, 2024, decision in Garland v. Cargill. The Supreme Court ruled that the ATF exceeded its authority with the 2018 final rule (“Bump-Stock-Type Devices”), which had classified bump-stock-type devices as “machine guns.” The Court held that a semi-automatic rifle equipped with a (non-mechanical) bump stock does not fire more than one shot “by a single function of the trigger” or “automatically,” as required by the statutory definition in the National Firearms Act (NFA, 26 U.S.C. § 5845(b)) and the Gun Control Act.
The new rule removes the two sentences added by the 2018 bump stock rule. This change is the direct result of the Supreme Court’s Cargill ruling.
The removed sentences are:
“For purposes of this definition, the term ‘automatically’ as it modifies ‘shoots, is designed to shoot, or can be readily restored to shoot,’ means functioning as the result of a self-acting or self-regulating mechanism that allows the firing of multiple rounds through a single function of the trigger; and ‘single function of the trigger’ means a single pull of the trigger and analogous motions.”
“The term ‘machinegun’ [or ‘machine gun’] includes a bump-stock-type device, i.e., a device that allows a semi-automatic firearm to shoot more than one shot with a single pull of the trigger by harnessing the recoil energy of the semi-automatic firearm to which it is affixed so that the trigger resets and continues firing without additional physical manipulation of the trigger by the shooter.”
Although bump stocks have been removed from the definition, many are concerned that not all problematic language was eliminated. The pre-2018 definition described a machine gun as “a firearm originally designed to fire, or capable of being fired fully automatically by a single pull of the trigger.” That language was altered in the 2018 bump stock rule. Many had hoped the new rule would simply revert to the original pre-2018 text, but it did not. Instead, the revised definition still expands the meaning of a “machine gun” beyond the pre-2018 version.
The new definition reads:
“A ‘machinegun,’ ‘machine pistol,’ ‘submachinegun,’ or ‘automatic rifle’ is a firearm which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.”
While this wording may seem trivial under the current ATF, future administrations could use the expanded definition to target items such as parts kits. Additionally, the rule’s deliberate failure to distinguish between non-mechanical and mechanical bump stocks leaves a gray area, preserving room for future case-by-case enforcement actions against other devices.
A future ATF could reinterpret what constitutes a machine gun without needing new legislation or even a new rulemaking.
We have already seen the Biden administration weaponize the ATF against lawful gun owners, and the vague wording in this rule could reopen that door for future administrations, particularly regarding items like forced reset triggers (FRTs).
ATF’s 34-Rule Reform Package Is a Start, Not a Finish Line for Gun Owners
About John Crump
Mr. Crump is an NRA instructor and a constitutional activist. John has written about firearms, interviewed people from all walks of life, and on the Constitution. John lives in Northern Virginia with his wife and sons. Follow him on X at @right2bear or at www.crumpy.com.
