Supposedly 2,000 guns a day crossing the border from the U.S. into Mexico

This claim seems no more believable than the 90 percent of Mexican crime guns coming from the US.

A November 2008 study by The Brookings Institution, a Washington-based think tank, stated that 2,000 American guns are smuggled into Mexico each day. Compiled by a commission including ex-Mexican President Ernesto Zedillo and Thomas Pickering, a former ambassador to Russia and a senior State Department official during the administration of President Bill Clinton, the report was the last comprehensive estimate on the subject, though it did not include information on how that figure was reached. . . .

That figure comes to 730,000 guns per year. If 14 million guns a year are sold in the US (the number of NICS checks in 2009 so this is obviously an underestimate, but it also includes background checks for concealed carry permits and sales of used guns), that means that roughly 5% of all U.S. guns manufactured each year were being smuggled illegally across the border.