A California man has been sentenced to three and a half years in prison for unlawfully manufacturing and dealing in CNC milled firearms and possession of an unregistered machine gun.

Daniel Crowninshield of Sacramento was arrested in 2014 for work at C&G Tool, a metal shop in North Sacramento. Marketing himself as 'Dr. Death,' Crowninshield made lower receivers for AR-15s and other firearms. The lower receiver holds mechanical parts like the hammer, bolt, and firing mechanism that combine with a trigger, firing pin, and other parts to make up a firearm, and can cost anywhere from $50 to $300. Customers would give Crowninshield a metal casting known as a blank, and he would then use a CNC mill to turn that casting into a fully-functioning lower receiver.

CNC mills have gone down significantly in price over the last few years, thanks to various Kickstarter projects and general market competition.While CNC mills and 3D printers often accept the same file formats, the machines are very different. Mills use a subtractive method, starting with a block of solid materials like Crowninshield's blanks and removing all the parts that are not needed.

It is legal to build your own gun, and modding out AR-15s is popular. But in order to sell one, you are required to have a license from the Bureau of Alcohol, Tobacco, and Firearms (ATF) and all guns must have a serial number. Crowninshield had no license, and his lower receivers had no serial numbers. In order to give the pretext that customers were building their own guns, Crowninshield would have customers place their hands on various buttons on the CNC mill so they could claim to be making it themselves.

But CNC mills are complex machines, taking far more than the push of a button to make something as complex as working gun parts. To properly make them, one would need to know how to program in G-code, utilize a post processor to convert a CAD/CAM drawing to cut a path, or at the least be able edit a generic cut path routine. Crowninshield would advertise his technical expertise and the Dr. Death brand on gun forums, where he also received positive reviews.

An undercover(UC) agent busted Crowninshield. On May 3, 2013, the agent

…took one of the blanks and assembled a jig around the blank. Crowninshield then directed the UC to place the blank into a CNC machine, owned by Crowninshield at C&G Tool and used to mill out machine parts. Crowninshield then directed the UC to close the safety door on the CNC machine and to hit a specific button to start the machine. During this time, the UC observed another customer that appeared to be doing the same thing at another machine. The UC overheard Crowninshield and another employee discussing a customer purchasing blanks. These blanks were known colloquially as blanks because they purportedly constituted 80 percent of a completed firearm and could be milled out at machine shops into completed firearms. The UC inquired if Crowninshield sold such blanks. Crowninshield showed the UC an inventory of such blanks for sale. The UC purchased a blank for $260, a gray blank for $180, and an aluminum blank for $160, all from Crowninshield.

The agent ultimately paid Crowninshield a total of $920 for those two blanks and for the service of milling the four lowers. Crowninshield never asked the agent to fill out any purchasing paperwork or about completing a background check. These component also had no serial numbers.

In sentencing, U.S. District Judge Troy L. Nunley referred to Crowninshield's actions as a "brazen attempt to circumvent the law."

"The unregulated manufacture and sale of high-capacity firearms is a serious threat to public safety," said U.S Attorney Phillip A. Talbert. "We will continue to investigate and prosecute unlicensed gun dealers who circumvent the law." Crowninshield's attorney did not respond to multiple attempts for comment.

Source: Department of Justice via Ars

CORRECTION: An earlier version of this article incorrectly stated that Crowninshield was using 3D printing to make his gun parts. He was using a CNC mill.

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