On the afternoon of Monday, March 22, a gunman killed ten people at a grocery store in Boulder, Colorado, using an AR-15-style pistol modified with an arm brace and fired rifle rounds. The AR Pistol Brace attachment allows a shooter to fire an easily concealable gun with rifle-like accuracy and firepower. 

As early as 2017, Giffords identified the threat of particularly dangerous firearms such as the AR-15 style assault pistol and stabilizing braces. Guns that fire rifle rounds are far more lethal than traditional pistols that fire handgun ammunition. Patrol officers wear ballistic-resistant vests rated to defeat handgun ammunition while assaulting pistols fire rifle rounds to penetrate protective vests.

In 2015, ATF determined that AR pistols with arm braces are short-barreled rifles since they can be fired from the shoulder and have a barrel that is shorter than 16 inches in length. However, in March 2017, ATF clarified that a pistol with an arm brace attached is not a short-barreled rifle unless the arm brace is being used with the intent to fire the weapon from the shoulder. ATF's decision fails to address the significant public safety threat posed by these pistol arm braces.

On February 11, 2019, a shooter killed a police officer with an AK-47 style assault pistol during an enforcement operation. Four days later, Rep. Val Demings (FL-10), a former police chief, introduced legislation that would regulate AR-15 and AK-47 style assault pistols under the National Firearms Act. Congress failed to pass this legislation, and on August 4, 2019, a mass shooter killed nine people and injured 17 in Dayton, OH using an AR-15 style assault pistol.

The National Firearms Act

On December 18, 2020, ATF published notice that it intended to consider enhanced firearms regulation with stabilizing braces under the National Firearms Act.

The National Firearms Act (NFA), enacted in 1934, was the first significant federal regulation on the manufacture, transfer, and possession of firearms. To possess firearms that fall under the NFA, individuals must undergo a background check process that includes the submission of photo identification and fingerprints and then must register the gun with ATF. Individuals must also pay a $200 transfer tax, which has not changed since the NFA was established in 1934. As of February of 2018, over 5.5 million NFA firearms were registered with ATF.

Because of the NFA's effective regulatory regime, weapons covered by the NFA are rarely used in crime. But few firearms fall within the NFA's purview. Of the 322,078 firearms traced in the United States during 2017, fewer than 1% were regulated under the NFA, including 1,265 machine guns and 1004 silencers. While the gun lobby often claims that gun laws don't work because criminals don't follow the law, the NFA has effectively deterred violent criminals from using these weapons.

Weapons regulated under the NFA include:

• Short-barreled rifles (SBRs) and sawed-off shotguns. These guns are particularly lethal because they can be easily concealed and also fire large-caliber rounds.
• Firearm silencers. These devices make it difficult to recognize the sound of gunfire and mask muzzle flash. They also make it difficult for nearby people, including law enforcement, to identify gunshots' sound and locate an active shooter.
• Fully automatic firearms, known as machine guns. In 1986, the Firearms Owners' Protection Act (FOPA) built on the NFA by banning the possession and transfer of new machine guns by a private citizen. Such weapons are particularly lethal because of their high rate of fire.
• "Destructive devices," including most large-caliber firearms. The provision adding these particularly lethal, large-caliber guns to the NFA was added in the 1960s.
• Devices that can convert a gun into a machine gun or destructive device, and any combinations of parts that can be used to build a machine gun or a destructive device. ATF has recently reclassified bump stocks to fit within this category.
• AOWs. AOW stands for "any other weapon," a catchall phrase used by the NFA intended to cover certain technologically unique weapons, including firearms that can be easily concealed but are not typical handguns.

Elected leaders in the 1930s made their best effort to identify and describe all categories of dangerous weapons that posed a danger to public safety. Unfortunately, this effective regulatory structure is under fire, both through modern technological hacks by the gun industry and through legislation pushed by the industry's key ally: the gun lobby.

The Gun Lobby's Dangerous Push Towards Deregulation 

The gun industry has been aggressively developing new weaponry since the NFA was first enacted. Through innovative and unconventional methods, they've also developed extremely lethal weaponry designed to avoid the law's requirements. 

The NRA reacted immediately when they noticed the pending action to consider enhanced firearms regulation with stabilizing braces under the National Firearms Act. On December 22, 2020, Rep. Richard Hudson (NC-08) and 89 other Congress members sent a letter to DOJ/ATF detailing their concerns over the proposed action.

Former Attorney General Barr's resignation was announced December 12, and his last day in office was December 23. Hours after his resignation, ATF withdrew the notice after consultation with the Office of the Deputy Attorney General. The NRA then took credit for the withdrawal of the information.

ATF has taken no action to restart actions that were stopped during the lame-duck Trump administration