Jim Norrell nailed it in his "Project GunRunner" article (July 2011 American Rifleman). The very idea that the Mexican drug cartels are dependent upon mom-and-pop corner gun shops in the US for their firearms is so far-fetched as to be ludicrous. I watched Greta van Susteren and the regional BATF supervisor discussing, in the Arizona desert, how "90% of the drug cartels guns came from US suppliers," as they stood beside a table of firearms. I nearly fell out, as prominently displayed on the table were a 1919 Browning machine gun, a Barrett .50 BMG, and a stack of AK-47s. I can't ever remember seeing a crew-served machinegun in a gun store, and I'm an old coot. Most of those in Class-III-licensed civilian hands are jealously guarded and worth a bloody fortune. Yes, US civilians can buy the Barretts, but there are few stores that can invest $10,000 in a rifle like that on the off-chance someone will wander in and buy it. Most are special-ordered. And why any cartel kingpin would waste his time and money buying semi-auto AK-47s at $450 a pop, when they can buy plane loads of fully-automatic ones from international arms dealers at $75/each is completely beyond me. Sure, if the BATF makes it easy to pick up a couple thousand semi-autos (which they obviously did), they'll take them to arm their local flunkies, but they're far more likely to do large purchases through the Russian or Columbian arms dealers. They also get many of their military firearms via Mexican Army deserters, who take their firearms with them (furnished courtesy of the US Armed Forces), which is where, I'm sure, that Browning machine gun came from.