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ATF Rulings on ‘Bump Stocks’

Q: Did the Obama administration legalize “bump stocks” for semiautomatic rifles?

A: No federal law explicitly addresses “bump stocks.” The Bureau of Alcohol, Tobacco, Firearms and Explosives ruled 10 times between 2008 and 2017 that certain models could not be prohibited under existing gun laws.


I just read on AOL that Trump announced (via tweet of course) the Obama administration legalized the sale of bump stocks. True or false? Naturally, he now takes credit for outlawing them. Please set the record straight.


A “bump stock” is a plastic or metal device that can be attached to the rear of a semiautomatic rifle to make it shoot almost as fast as a fully automatic weapon. The stock uses recoil to make the weapon bump back and forth between the shooter’s shoulder and trigger finger, causing the firearm to fire rapidly.

The devices became part of the gun debate in October after 64-year-old Stephen Paddock used AR-style rifles affixed with bump stocks to shoot people attending an outdoor concert in Las Vegas. More than 50 people were killed and hundreds more were injured.

Then, in February, after another deadly mass shooting at a Florida high school, President Donald Trump directed Attorney General Jeff Sessions to look into “banning all devices that turn legal weapons into machineguns.” The Department of Justice announced on March 23 that it was proposing a rule to that effect.

That same day on Twitter, Trump faulted former President Barack Obama for the devices, saying it was a “bad idea” that his administration had “legalized” bump stocks. Since then, a number of FactCheck.org readers have emailed us, inquiring whether the gun accessories were allowed during Obama’s presidency.

The president’s tweet may have left some with the false impression that bump stocks had been illegal and the Obama administration made some change in the law. That’s not the case. Instead, whether bump stocks are legal depends on how exactly different models function. At issue is whether the devices meet the definition of “machinegun” under federal firearm laws, which have prohibited, with some exceptions, the transfer and possession of a “machinegun” since 1986.

Federal law defines a machine gun as a weapon that “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 definition says it also includes “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.”

In December, the Department of Justice announced it would launch a regulatory process “to determine whether bump stocks are prohibited.”

It’s true that, under Obama, the ATF — an agency within the Justice Department — ruled that it could not prevent the use of certain models of bump stocks.

In June 2010, for example, the bureau responded to a request to evaluate a product sold by Slide Fire Solutions, a Texas company that makes the devices. In a letter, John Spencer, then the ATF’s Firearms Technology Branch chief, wrote that the device examined had no “functioning mechanical parts or springs” that made it perform like an automatic weapon.

“In order to use the installed device, the shooter must apply constant forward pressure with the non-shooting hand and constant rearward pressure with the shooting hand,” Spencer said. “Accordingly, we find that the ‘bump-stock’ is a firearm part and is not regulated as a firearm under Gun Control Act or the National Firearms Act.”

The ATF, under Trump, also made a similar determination in April 2017, about a different model of bump stock.

In that letter, Michael Curtis, the head of ATF’s Firearms Technology Industry Services Branch, wrote: “The FTISB examination of the submitted device indicates that if as a shot is fired — and a sufficient amount of pressure is applied to the handguard/gripping surface with the shooter’s support hand — the AR-type rifle assembly will come forward until the trigger re-contacts the shooter’s stationary firing-hand trigger finger: Re-contacting allows the firing of a subsequent shot. In this manner, the shooter pulls the receiver assembly forward to fire each shot, each succeeding shot firing with a single trigger function.”

“Since your device does not initiate an automatic firing cycle by a single function of the trigger,” Curtis said, “FTISB finds that it is NOT a machinegun under the [National Firearms Act], or the amended [Gun Control Act].”

In fact, in a notice of proposed rulemaking published in the Federal Register in December, the ATF said “since 2008,” which predates Obama’s time in office, “ATF has issued a total of 10 private letters in which it classified various bump stock devices to be unregulated parts or accessories, and not machineguns or machinegun conversion devices as defined” in federal gun laws.

The letters were sent to individuals and manufacturers who voluntarily submitted devices for classification. Because the letters are private, the ATF does not make them readily available to the public without the recipient’s consent.

Slide Fire posted its June 2010 letter from the ATF on its website. The letter the ATF sent in 2017 under Trump was obtained from the Justice Department by the Giffords Law Center and Democracy Forward, which, according to BuzzFeed, filed a request under the Freedom of Information Act. The recipient’s name was redacted.

We asked the ATF for the dates the letters were sent, and we were referred to the agency’s March 29 rulemaking proposal that only mentions a range of 2008 to 2017. Still, that suggests that at least one of the letters was sent during the George W. Bush administration. That’s in addition to the letter we know was issued under Trump’s administration.

Some bump stocks have been deemed illegal, though.

In an April 2013 letter to Democratic Rep. Ed Perlmutter, Richard Marianos, then ATF assistant director for public and governmental affairs, wrote: “Those bump-fire stocks which were found to convert a weapon to shoot automatically were classified as machineguns and regulated accordingly, most notably, the Akins Accelerator.”

Marianos said the Akins Accelerator, an attachment patented by former U.S. Marine Bill Akins in 2000, “incorporated a mechanism to automatically reset and activate the fire-control components of a firearm” after a single pull of the trigger. That meets the definition of a machine gun. The ATF ruling was made in 2006, and was later upheld by a federal appeals court.

On the other hand, Marianos said devices like the Slide Fire stock, which “requires continuous multiple inputs by the user for each successive shot,” could not be classified as a restricted firearm. “Therefore, ATF does not have the authority to restrict their lawful possession, use, or transfer,” he said.

The ATF under Trump now disputes that interpretation and wants to classify all bump stocks as federally banned weapons.

Its proposed rule seeks to clarify that a machine gun includes “bump-stock-type devices, i.e, devices that allow a semiautomatic firearm to shoot more than one shot with a single pull of the trigger by harnessing the recoil energy of the semiautomatic firearm to which it is affixed so that the trigger resets and continues firing without additional physical manipulation of the trigger by the shooter.” The agency says it has reviewed the “relevant statutory language” and determined that bump stocks do turn semiautomatic firearms into automatic ones.

It argues: “When a shooter who has affixed a bump-stock-type device to a semiautomatic firearm pulls the trigger, that movement initiates a firing sequence that produces more than one shot. And that firing sequence is ‘automatic’ because the device harnesses the firearm’s recoil energy in a continuous back-and-forth cycle that allows the shooter to attain continuous firing after a single pull of the trigger, so long as the trigger finger remains stationary on the device’s ledge (as designed). Accordingly, these devices are included under the definition of machinegun and, therefore, come within the purview of the [National Firearms Act].”

The proposed rule would require those who possess, sell or make bump stocks to destroy them, surrender them or permanently render them inoperable.

Trump, though, got ahead of himself during a speech in Ohio on March 30 when he claimed that his administration “got rid of the bump stocks,” but “nobody reported it.” In fact, some bump stocks are still legal. A final rule cannot be issued until after the public comment period ends June 27.

Even then, gun rights groups and advocates have said any final rule could be challenged in court. They argue that the ATF is changing the definition of a machine gun, which they say can only be done by Congress.

Sen. Dianne Feinstein agrees with that assessment. She, along with fellow Democratic Sens. Richard Blumenthal and Chris Murphy, introduced a bill in October that would ban bump stocks and similar devices. It has received a committee hearing, but not a vote.

“If ATF tries to ban these devices after admitting repeatedly that it lacks the authority to do so, that process could be tied up in court for years, and that would mean bump stocks would continue to be sold,” Feinstein said in a statement in February.

“Legislation is the only answer,” she said.


Buchanan, Larry, et al. “What Is a Bump Stock and How Does It Work?” New York Times. 20 Feb 2018.

ATF: Las Vegas shooter had 12 guns modified to mimic automatics – live updates.” CBS News. 3 Oct 2017.

White House. “Presidential Memorandum on the Application of the Definition of Machinegun to ‘Bump Fire’ Stocks and Other Similar Devices.” 20 Feb 2018.

Rose, Veronica, and Reilly, Meghan. “Summary of State and Federal Machine Gun Laws.” Office of Legislative Research, Connecticut General Assembly. 12 Jan 2009.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. National Firearms Act. Atf.gov. 1 Dec 2016.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. Letter to Slide Fire. 7 Jun 2010.

U.S. Department of Justice. “Attorney General Sessions Announces Regulation Effectively Banning Bump Stocks.” Press release. 23 March 2018.

U.S. Department of Justice. “Justice Department and ATF Begin Regulatory Process to Determine Whether Bump Stocks Are Prohibited.” Press release. 5 Dec 2017.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. Letter about bump stock device. 6 Apr 2017.

Holden, Dominic. “Documents Show The Trump Administration Approved Bump Stocks Before It Opposed Them.” BuzzFeed. 22 Mar 2018.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. “Application of the Definition of Machinegun to ‘Bump Fire’ Stocks and Other Similar Devices.” Federal Register. 26 Dec 2017.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. “Bump-Stock-Type Devices.” Federal Register. 29 Mar 2018.

U.S. Department of Justice, Bureau of Alcohol, Tobacco, Firearms and Explosives. Letter to Rep. Ed Perlmutter. 16 Apr 2013.

Ax, Joseph. “Inventor of ‘bump stock’ spent years fighting for device, and lost.” Reuters. 6 Oct 2017.

Krouse, William. “Gun Control: ‘Bump-Fire’ Stocks.” Congressional Research Service. 10 Oct 2017.

White House. “Remarks by President Trump on the Infrastructure Initiative.” Transcript. 30 Mar 2018.

Wheeler, Lydia. “Trump sets up legal fight over bump stocks.” The Hill. 27 Mar 2018.

Feinstein, Dianne. “Feinstein on Bump Stocks: Legislation is the Only Answer.” Press release. 20 Feb 2018.

Blumenthal, Richard. “Blumenthal and Murphy Introduce Bill to Close Automatic Weapon Loophole.” Press release. 4 Oct 2017.

S.1916 – Automatic Gunfire Prevention Act. Congress.gov. As introduced 4 Oct 2017.

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Friday, March 23, 2018