A ridiculous discussion on the 'Weapons seized from Drug Cartels by Mexican Army' thread at Militaryphotos.net about where the guns are actually coming from has turned to angst. Seems some people just know that it's America's fault.
Let me point out something really obvious to everyone. It doesn't matter where a drug cartel thug requisitioned his Colt rifle from in regards to traceability, whether it be he deserted the military and took his issued weapon, or bought it from Billy Bob's gun shack in Arizona, or payed some starving Mexican Federale for his, because every Colt rifle starts life in the same exact place. So no shit the rifle can be "traced back to the US!" That's where it was made! Virtually all AR type rifles are manufactured in the US, so of course they're going to be traced there. I bet every one of the Chevy Tahoes that the cartels use to deliver a car bomb can be traced back to the US too!
From browsing this thread and comparing it to the Mexican Armed Forces thread, it's easy to see that a lot of the heavy hardware starts its service in the hands of Mexican government employees and somehow makes its way into the hands of the cartels. You can argue how that is happening all you want, or not happening, or can't happen, but in every other picture of captured cartel weapons there are those shiny gold canisters that are about 40mm in diameter, and if you look close you can also see them here. Hmmmmm.
Also, the grenades that the cartels use originated in the US too. I gather that the LAW rockets and M203s did as well, and probably the M18 claymores. So don't get all wrapped up around the axle when some alphabet news man or internet commando says that the cartels get weapons from the US. Smile knowing that every one of the 8,000,000+ M16/AR15 pattern weapons that the US brokered to Mexico can be traced back stateside, and then ask is it possible that the cartels may be getting them from the corrupt Mexican government. Trace them all you want to; we know where they're getting them!