Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

DOJ seal

Department of Justice

U.S. Attorney's Office
Middle District of Florida
Roger B. Handberg, United States Attorney
For Immediate Release
Friday, September 8, 2023

YouTuber and Auto Key Card Manufacturer Sentenced to Five Years in Prison for Transferring Unregistered Machinegun Conversion Devices

Jacksonville, Florida – U.S. District Judge Marcia Morales Howard has sentenced Kristopher Justinboyer Ervin (43, Orange Park) to five years and eight months in federal prison and Matthew Raymond Hoover (39, Wisconsin) to five years in federal prison for conspiring to transfer and transferring unregistered machinegun conversion devices. Ervin additionally was sentenced for structuring cash withdrawals from his bank account consisting of proceeds of the sale of the devices. The court also ordered Ervin to forfeit $68,000, representing the amount of funds involved in the structuring offense. Ervin and Hoover were found guilty by a federal jury on April 21, 2023.

According to court documents, in January 2021, Ervin’s bank contacted the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) to report that employees believed that Ervin was trafficking in machinegun conversion devices. Subsequent investigation revealed that Ervin was running an online business selling machinegun conversion devices, known as lightning links, etched into metal cards, which he referred to as Auto Key Cards. Ervin described the Auto Key Card as a “pen holder,” a “novelty,” and a “political sculpture.”

In February 2021, federal agents from ATF and the U.S. Postal Inspection Service (USPIS) surveilled Ervin and observed him dropping off dozens of packages at an Orange Park post office, each of which was determined to contain unregistered machinegun conversion devices. A lightning link can be dropped into an otherwise legal AR-15 type firearm and convert it into a fully automatic machinegun.

ATF examined the Auto Key Cards, and a firearms enforcement officer was able to remove the pieces of a lightning link from an Auto Key Card using a common Dremel rotary tool in about 40 minutes. When the firearms enforcement officer placed the two pieces of the lightning link into an AR-15 type firearm, it converted the semi-automatic firearm to be fully automatic – that is, a machinegun.

Hoover operated a YouTube channel called CRS Firearms on which he advertised Auto Key Cards. Hoover stated that his viewers could cut a lightning link out of the Auto Key Card, “drop it in your receiver, scratch your full auto itch, throw it away when you’re done” and “no one’s the wiser.”

Hoover’s videos advertising the Auto Key Card led to a substantial increase in Ervin’s sales. Ervin sold more than 2,000 Auto Key Cards in only a few months. Multiple purchasers of the Auto Key Card testified at trial that they had learned about it from Hoover’s videos and purchased the Auto Key Card intending to use it to convert their AR-15 type weapons into machineguns. Ervin compensated Hoover for his advertisements by sending cash through the mail and, on one occasion, a Louis Vuitton purse.

In March 2021, federal agents executed a search warrant at Ervin’s home and recovered Auto Key Cards containing etchings for more than 1,500 lightning links. In total, the evidence showed that the conspiracy involved at least 6,600 individual lightning links.

This case was investigated by the Bureau of Alcohol, Tobacco, Firearms and Explosives, the U.S. Postal Inspection Service, and the Internal Revenue Service – Criminal Investigation. It was prosecuted by Assistant United States Attorneys Laura Cofer Taylor and David B. Mesrobian. The asset forfeiture is being handled by Assistant United States Attorney Mai Tran.

“Investigating this case required dedication and tenacity on behalf of ATF’s Jacksonville Field Office and our partner agencies on this matter—the U.S. Postal Inspection Service, Internal Revenue Service and the U.S. Attorney’s Office,” said ATF Tampa Field Division Special Agent in Charge Kirk Howard, whose agency led the investigation. “Our work was necessary to prove the true nature of the Auto Key Cards being sold by Ervin and Hoover and disrupt their audacious scheme to circumvent federal firearms laws.”

This case is part of Project Safe Neighborhoods (PSN), a program bringing together all levels of law enforcement and the communities they serve to reduce violent crime and gun violence, and to make our neighborhoods safer for everyone. On May 26, 2021, the Department launched a violent crime reduction strategy strengthening PSN based on these core principles: fostering trust and legitimacy in our communities, supporting community-based organizations that help prevent violence from occurring in the first place, setting focused and strategic enforcement priorities, and measuring the results.

Anyone in possession of an Auto Key Card should contact his or her nearest ATF office or call 1-800-ATF-GUNS and make arrangements to surrender the device to ATF so that it can be destroyed.


An official website of the U.S. Department of Justice

Looking for U.S. government information and services?