Bump-fire devices are just one type of a variety of attachments sold in the United States to increase the rate of fire of semiautomatic firearms to mimic the firepower of a fully automatic machine gun. Most of these devices have been determined to be legal and can be sold unencumbered by gun laws. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is in charge of reviewing such devices to determine whether they enable a firearm to actually function as a machine gun−in which case they are illegal to possess pursuant to the federal ban on the possession by private citizens of machine guns manufactured after May 19, 1986.
ATF Opinion Letters on Devices to Increase the Rate of Fire of Semiautomatic Firearms
Read the letters from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) on the legality of various bump-fire and other devices designed to enable semiautomatic firearms to mimic fully-automatic machine gun fire.
Akins Accelerator, June 26, 2008 – Device approved
Foeller device, June 18, 2008 – Device approved
Slide Fire, June 7, 2010 – Device approved
Historic Arms SKS device, May 25, 2011 – Device approved
3MR trigger assembly, October 31, 2013 — Device approved
Echo Trigger, November 20, 2013 – Device approved
AutoGlove device, September 11, 2017 – Device ruled “machinegun”