Gee, so they're not buying RPGs at gun shows?

Wow, I that that was a settled consensus, like globular warmering...
Reporting from Zihuatanejo, Mexico, and Mexico City -- It was a brazen assault, not just because it targeted the city's police station, but for the choice of weapon: grenades.

The Feb. 21 attack on police headquarters in coastal Zihuatanejo, which injured four people, fit a disturbing trend of Mexico's drug wars. Traffickers have escalated their arms race, acquiring military-grade weapons, including hand grenades, grenade launchers, armor-piercing munitions and antitank rockets with firepower far beyond the assault rifles and pistols that have dominated their arsenals.

Most of these weapons are being smuggled from Central American countries or by sea, eluding U.S. and Mexican monitors who are focused on the smuggling of semiauto- matic and conventional weapons purchased from dealers in the U.S. border states of Texas, New Mexico, Arizona and California.

Yes, the article still hits the talking points that 'most of the problem up to now is due to lax US gun laws', etc. ad blargh. But:
These groups appear to be taking advantage of a robust global black market and porous borders, especially between Mexico and Guatemala. Some of the weapons are left over from the wars that the United States helped fight in Central America, U.S. officials said.
Damn, they actually pointed out an Inconvenient Truth: It Ain't Our Fault.

How many weapons have been smuggled into Mexico from Central America is not known, and the military-grade munitions are still a small fraction of the larger arsenal in the hands of narcotics traffickers. Mexican officials continue to push Washington to stem the well-documented flow of conventional weapons from the United States, as Congress holds hearings on the role those smuggled guns play in arming Mexican drug cartels.
As has been pointed out before, this is bullcrap. And if it's not, why won't the Mexican government supply the serial numbers of weapons they've seized to the US government? If the guns were 'legally' bought here and smuggled into Mexico, the serial numbers would tell exactly who imported or manufactured them, and what dealer sold them; so the only reason for the Mex government to refuse to supply them is they know they didn't come from here. And giving us the numbers would prove it; and since blaming us is so handy for that government...

And now we get to the real meat:
The enhanced weaponry represents a wide sampling from the international arms bazaar, with grenades and launchers produced by U.S., South Korean, Israeli, Spanish or former Soviet bloc manufacturers. Many had been sold legally to governments, including Mexico's, and then were diverted onto the black market. Some may be sold directly to the traffickers by corrupt elements of national armies, authorities and experts say.
And there it is. Those Barrett rifles that are supposedly so 'easily' being smuggled into Mexico?(maybe we need a fence, huh?) Remember this picture?

I'm doing it, I'd suggest you contact your congresscritters and point out this article, in particular the parts noting that this crap isn't coming from US gun shops and shows.