Illegally trafficked weapons are difficult to count, but there is a lot of sound data to indicate that U.S.-sourced assault weapons are more commonly used in violent crimes in Mexico than in the United States.
According to records of the Mexican justice department (Procuraduría General de la República, or PGR), which keeps data on firearms recovered from crime scenes, of 93,078 guns recovered from 2006 through 2017, more than 40% (38,409) were long guns.[i] Most of those long guns were likely semi-automatic assault rifles.
That is because organized criminal groups use military-grade assault weapons in order to control territory. Assault weapons that are freely available at retail gun shops in Texas, Arizona, and other U.S. states are thus an excellent source of weaponry for those groups.
The Mexican military also keeps records of weapons it has recovered, including the information on caliber and manufacturer. Of 66,011 firearms recovered between 2006 and March 2018 for which the caliber and make were recorded, more than 12,000 could be positively identified as assault weapons. More than 2,000 of these assault weapons were produced by a single manufacturer, Colt Defense Industries of Hartford, Connecticut, more than any other gun maker.[ii]
Other estimates, such as a recently released report by The Wilson Center, put the portion of assault weapons at close to half the crime guns recovered in Mexico.
Private citizens in Mexico may not legally purchase assault weapons, which are restricted principally to government forces.
[i] See Procuraduría General de la República, response to public records request, Folio 0001700052217.
[ii] See Secretaría de Defensa Nacional (SEDENA), response to public records request, Folio 0000700097618.