Trump Admin Tells Congress ‘No Reliable Evidence’ Exists Showing Gun Microstamping Works

The Trump administration told a senior member of Congress it had no proof showing that a “microstamping” mandate would make firearms more traceable.

Republican Rep. Brian Babin of Texas, who chairs the House Science Committee, asked the National Institute of Science and Technology (NIST) to answer questions about the reliability, durability, manufacturing consistency and forensic utility of microstamping — the use of a device to leave an identifiable series of marks on a bullet cartridge — in a February 2025 letter to the agency. NIST sent its response to Babin in the form of a seven-page letter dated August 12.

“NIST has not conducted independent research in this area, nor does the agency currently have an active workstream on this topic,” NIST told Babin. “Establishing a robust scientific validation across real-world conditions would require substantial resources. Our response offers a synthesis of published data from state agencies, academic institutions, forensic science professionals, and advocacy groups. NISTs goal in this response is to provide the Committee with a comprehensive summary of the best available evidence in the field.”

“Microstamping” involves a firearm using a modified firing pin or other device to leave an identifiable series of marks on a bullet cartridge that could be recovered at the scene of a crime, according to a fact sheet from the National Rifle Association’s (NRA) Institute for Legislative Action. California, New York and New Jersey have passed legislation that will eventually require the technology on firearms, according to The Truth About Guns.

Pro-Second Amendment organizations have raised concerns about “microstamping” mandates, arguing the technology has issues with reliability and would add as much as $200 to the cost of a firearm. In the letter, NIST noted the technology could also be easily circumvented.

“The technology is highly susceptible to deliberate circumvention. Microstamps on firing pins can be defaced or obliterated with basic household tools such as a sharpening stone, hammer, or small file,” NIST wrote. “The research demonstrated that the firearm remained fully operational after removing the microstamp. Furthermore, because firing pins are replaceable parts, a user could easily swap a microstamped pin for an unmarked aftermarket version.”

“It is important to note that replacing a firing pin can be part of routine maintenance or accommodate an owner’s preference,” NIST continued. “NO realistic mechanical mitigation strategy currently exists to address these modifications, and critics argue this vulnerability undermines the technology’s effectiveness as a crime-solving tool.”

The last time legislation mandating the use of microstamping was introduced in Congress was on Jan. 23, 2019, when then-Democratic Rep. Anthony Brown of Maryland sponsored H.R. 719, the Make Identifiable Criminal Rounds Obvious (MICRO) Act, but the bill died in the House Judiciary Committee.