Panel divided over gun-rule changes: DOJ urges penalties for machine-gun conversion devices; defenders warn of disparate impact

At a public hearing before the United States Sentencing Commission, the Department of Justice urged broad changes to the firearms guideline to address machine-gun conversion devices (MCDs) and to retain or lower proof requirements for enhancements tied to stolen or serial-number-altered firearms.

Assistant U.S. Attorney Paige Messick argued that conversion devices are inherently dangerous and that the guideline currently fails to reflect the cumulative risk posed when an MCD is paired with a large-capacity magazine or sold to a prohibited person. "An unaffixed MCD is not a collector's item. It's not a trinket," Messick said. "If you have an MCD, you're almost certainly either intending to use it to turn your gun into a machine gun or you're planning to transfer it to someone so they can turn their gun into a machine gun."

DOJ and elements of the criminal-law bench also objected to adding a mens rea requirement for stolen firearms and for firearms with modified serial numbers; they said strict liability or a low mens rea would better capture public-safety risk because many felon-in-possession encounters occur as unplanned contacts with law enforcement and records needed to prove knowledge are often not available. The department offered a rebuttable-presumption approach for mens rea as a compromise in written submissions.

Public defenders, the Practitioners Advisory Group and district-level defenders urged caution. Vivian Marrero, an assistant federal public defender in Puerto Rico, opposed a broad redefinition that would count each MCD the same as a fully automatic firearm, warning of "illogical results" and substantial racial and geographic disparities if fixed and unaffixed MCDs are scored identically. Michael Carter and others said expanding the guideline without precise, narrowly tailored language will sweep many low-level sellers into much higher ranges; they urged either a narrower MCD-specific enhancement (trafficking or quantity tiers) or further study before adoption.

Probation officers and victims advisers urged tailored drafting. The Probation Officers Advisory Group favored applying any expanded definition to the firearm-count subsection (so that number of devices scales the offense level) and recommended clear text on how to count affixed versus standalone MCDs. The Victims Advisory Group supported expansion to subsections that address trafficking and in-connection enhancements, citing ATF recoveries and a rise in MCD cases.

On mens rea, the Practitioners Advisory Group supported requiring knowledge or willful blindness for stolen or serial-number-modified enhancements, arguing deterrence requires mens rea and that many guideline mens rea provisions already function in other contexts; others on the panel noted evidentiary and administrative challenges. Several commentators noted an ATF finding cited at the hearing that roughly 1,000,000 firearms were stolen nationwide in 2017—-2021 and a 2024 ATF press release reporting 31,000 recovered MCDs over five years.

Why it matters: adding MCDs to the firearms guideline or altering mens rea for serial-number or theft enhancements would raise offense levels in many cases, changing plea negotiations and sentencing outcomes; careful drafting is needed to avoid unintended disparity or disproportionate impacts in particular districts.

What’s next: the commission requested more data, recommended clearer definitions (affixed vs. unaffixed; possession vs. trafficking) and said it would consider commenters' alternative drafting suggestions before finalizing any amendment.