The ‘Ghost Gun’ Linked to Luigi Mangione Shows Just How Far 3D-Printed Weapons Have Come

“It just speaks to the ease with which you can do this,” says Wilson. “He doesn’t have to be an expert at 3D-printed guns or shooting, and it all works.”

Despite its simple description by law enforcement and others as a “3D-printed pistol,” the FMDA 19.2 is only partially 3D printed. That makes it fundamentally different from fully 3D-printed guns like the “Liberator,” the original one-shot, 3D-printed pistol Wilson debuted in 2013.

Instead, firearms built from designs like the FMDA 19.2 are assembled from a combination of commercially produced parts like barrels, slides, and magazines—sometimes sold in kits—and a homemade frame. Because that frame, often referred to as a “lower receiver” or “lower,” is the regulated body of the gun, 3D-printing that piece or otherwise creating it at home allows DIY gunmakers to skirt gun-control laws and build ghost guns with no serial number, obtained with no background check or waiting period.

The FMDA 19.2 model, released by a group originally known as Deterrence Dispensed—a gun-building group initially inspired by Wilson’s Defense Distributed but now widely seen as a rival—was distinguished by its use of commercially available “rails,” the metal components that guide the upper part of the gun known as its slide, which retracts with every shot, resetting the trigger and loading a new round into the chamber. (In a widely circulated video of Thompson’s murder, the gun allegedly fired by Mangione appears not to have functioned as a semiautomatic. That’s a result of the suppressor attachment preventing its re-chambering mechanism, gunsmiths say.)

The FMDA 19.2’s relatively simple tweak—the use of commercially produced metal rails instead of homemade ones—led the gun model to be considered the most practical and reliable 3D-printed Glock design available at the time it was released three years ago. “There had been earlier Glock-style pistols, but the interior rail components were not as refined,” says Mr. Snow Makes. “It’s kind of that perfect blend of 3D-printed frame and precision rails.”

Deterrence Dispensed, the group behind that FMDA 19.2 design, has since rebranded under the name “the Gatalog.” But the group’s original website still bears the libertarian gun rights slogans that summarize its ideology. “All individuals are entitled to the utility to defend their humanity,” the site reads. “Gun control has failed. You can’t stop the signal.”