New internal documents from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) have been leaked to Gun Owners of America (GOA) and AmmoLand News.
The three leaked documents involve privately manufactured firearms (PMF), machinegun conversion devices (MCD), and tracing guidance. Two of the documents were created on January 15, 2025, and all are classified as “controlled unclassified information/LEI.” These documents were distributed to law enforcement agencies across the nation.
The first document explains to the police how to report MCDs to the ATF National Tracing Center (NTC). The ATF has added a new “PMF/MCD Recovery Report” option within eTrace, an electronic database that the ATF administers to log guns from crime scenes. Before last month, eTrace did not have options to enter information for PMFs or MCDs.
In the new system, the reporting party must enter the make and model of the host firearm to enter an MCD. For example, the ATF used a Glock 17 equipped with a switch that transforms a semiautomatic Glock into a machinegun. All other identifying marks are entered in the “Other identifying Marks” field.
When users enter an MCD into eTrace, they must select whether the device is a PMF and then enter its material and color. The ATF provides examples of MCDs, such as switches, invisi-switches, lighting legs, swift links, Yankee Boogles, and drop-in auto sears (DIAS) for both the AR-15 and AK platforms.
The second document provides tracing guidance for PMFs. When entering the firearm into eTrace, the end user must select the type of firearm recovered. The first category is “Completed Firearm.” The user must enter the caliber of the firearm, and any serial numbers found on the barrel or slide. Although most PMFs lack serial numbers, the barrels and slides are typically purchased separately, and those could be serialized.
The second category for PMFs is “Destructive Devices.” The ATF wants the user to enter information about the device’s material composition, color, and other identifying marks. The ATF uses a homemade grenade launcher as an example of a home-built destructive device.
The third category the user can select includes privately made frames and receivers. These items consist of pistol frames and AR receivers. Like destructive devices, the ATF requires the reporter to provide the material composition of the item and its color. There is also a field for the user to enter the number of recovered frames or receivers. The maximum number allowed on a single report is 500.
The final category is “Privately Made Silencers.” As with the other categories, the end user is required to input the caliber or gauge, material composition, and color of the homemade suppressor. Additionally, there is a field for users to specify the number of recovered home-built silencers. The maximum number permitted on a single report is 500. If the number exceeds 500, a second report is needed.
The document acknowledges that the absence of a serial number on PMFs does not render these items untraceable. This acknowledgment directly contradicts the ATF’s public position that PMFs are dangerous because the lack of serial numbers makes them untraceable.
The final internal document, released on October 23, 2024, explains how machinegun conversion devices work. The first MCD described in the document is a “switch.” It shows parts of the switch that anyone can use as a reference to produce one and explains how a switch works. It also highlights the “invisi-switch.” An invisi-switch is like a switch but rests flat at the back of the slide, making it less noticeable. An invisi-switch is easily printed on any 3D printer. The document gives examples of switches such as the Toothpick, Skreee, Best Auto Sear, and Classic Auto Sear.
The document’s second MCD is the “trigger control group travel reducer” (TCGTR), also known as a swift link. A swift link converts an AR-15 into a machine gun, usually made of a thin piece of bent metal.
The ATF appears to be concerned about 3D-printed machinegun conversion devices. It discusses the “Yankee Boogle,” one of the first 3D-printed MCDs. The Yankee Boogle functions like a swift link but is made using 3D printing. Other 3D-printed MCDs that the ATF has concerns about include the “Choosy Express,” the “Lightning Link” (3D-printed version), the “Spicy Meatball,” the “Bonus Spicy Meatball,” and the “Stoner Hightop.”
The fourth MCD the ATF is concerned about is drop-in auto sears, which converts a semiautomatic AR-15 into a machine gun. The document highlights that an M16 fire-control parts and bolt carrier are needed for a DIAS to function correctly.
The final MCD the ATF is worried about is the “Lightning Link.” This metal link has two parts: a horizontal link and a vertical paddle. The document explains that an SP-1-type bolt carrier is required and describes how the lightning link works.
These ATF documents could be used by the public as a guide to making MCDs, even though that isn’t the ATF’s intention. AmmoLand News thanks the brave whistle-blowers who are willing to share what should be public information with us.
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 @crumpyss, or at www.crumpy.com.
