But if you ask Dr. Shannon O'Neil - fellow for Latin America studies at the Council on Foreign Relations, she will tell you the answer is yes: US gun stores sell all of the above.
And not only that: somehow good Dr. O'Neill managed to count how many gun stores located along the Mexican-US border are engaged in selling hand grenades and RPG launchers to Mexican drug dealers: 7,000 (according to her there are three gun stores for every mile along the border)
Here is just a sample from Dr. O'Neill's wacademic research:
The gun situation is even worse. The Merida Initiative promises some sophisticated gear to the Mexican government, including helicopters, speedboats, and high-end database and surveillance systems. Yet the arms that cartels can and do buy from the open U.S. market -- completely illegally -- leave Mexico's police force and even its military outgunned. There are nearly 7,000 gun shops along the southern U.S. border, about three for every mile. They sell thousands of hand grenades, rocket-propelled grenade launchers, AK-47s, and "cop killer" guns and bullets that cut through Kevlar body armor. The weapons quickly flow south, again with barely a nod from U.S. Border Patrol.
The rest of her "scientific" study on what is causing drug and gang violence in Mexico is here
From Dr. O'Neill's bio:
Adjunct assistant professor of political science and visiting scholar, Institute of Latin American Studies, Columbia University (2006); Fulbright scholar in Mexico and Argentina; Justice, Welfare and Economics Fellow, Harvard University; Equity Analyst, Indosuez Capital Latin America and Credit Lyonnais Securities (1994-97)
As they say: in order to become such an idiot, a college degree is required.