Countering Illegal Firearms Trafficking to Mexico Act This bill amends the federal criminal code to make trafficking in firearms a stand-alone criminal offense. A person who commits or conspires to commit a gun trafficking offense is subject to criminal penalties—a prison term of up to 20 years (or up to 25 years, if the person also acted as an organizer), a fine, or both. The bill directs the President to design and implement a strategy to improve collaboration between the U.S. Immigration and Customs Enforcement and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) in the investigation of illegal firearms trafficking to Mexico. The Office of National Drug Control Policy must establish indicators to measure the progress of efforts to stem firearms trafficking to Mexico. The ATF must publish detailed information about each firearm seized by Mexican authorities and submitted to the ATF for tracing.