Actually you CAN own a
" Weapons may be kept in the home for security and legitimate defense of its dwellers. Their possession imposes the duty to manifest them to the Secretariat of National Defense for their registration. For every weapon, record of its registration will be issued."
And a secondary quote from wikipedia
"Under these two articles, private citizens are generally restricted to semi-automatic handguns or revolvers of a caliber no greater than
As far as I know, Aguila Ammunition is still manufactured in mexico, including
So the 100% Mexico ban you stated is little less than 100% imho.