Guns aren't banned in Mexico, and Mexico, like the US, has the right to bear arms written into their constitution.
As usual, you simply make shit up.
{n 1971, Article 10 of the present Constitution was reformed[11] to limit the right to keep arms within the home only (in Spanish: ...derecho a poseer armas en su domicilio...) and reserved the right to bear arms outside the home only to those explicitly authorized by law (i.e. police, military, armed security officers). The following year, the Federal Law of Firearms and Explosives came into force[12] and gave the federal government complete jurisdiction and control to the legal proliferation of firearms in the country; at the same time, heavily limiting and restricting the legal access to firearms by civilians.
As a result of the changes to Article 10 of the Mexican Constitution and the enactment of the Federal Law of Firearms and Explosives, openly carrying a firearm or carrying a concealed weapon in public is virtually forbidden to private citizens, unless explicitly authorized by the Secretariat of National Defense (SEDENA). For purposes of personal protection, firearms are only permitted within the place of residence and of the type and caliber permitted by law.}
Gun politics in Mexico - Wikipedia, the free encyclopedia