Overthrow the government

In the wake of the Virginia Tech massacre, new discussion are starting about gun control in the United States. As a European, the ready availability of firearms of any kind is nothing short of baffling to me. I know that Americans consider the Bill of Rights as something of a sacred text, and its Second Amendment is pretty unambiguous. But I would urge Americans to wake up and smell the statistics: other countries have astronomically less firearms-related crimes. And the problem is not the legality or illegality of firearms (because as gun lobbyists so rightly point out, outlawing guns puts guns in the hands of outlaws only), but their omnipresence: the reason people don't shoot each other nearly so much in, say, Denmark, is because there simply aren't so many guns being manufactured. How about setting a quota on gun production and imposing super-strong border checks?
Ah, say gun proponents, but there is another, vital part to the availability of guns: it allows the people to gather together and overthrow their government, by force if necessary. To these people I would say: here is your chance! If ever in the history of the United States a government was more in need of overthrowing than the Bush administration, I'd like to know which one it is. This government has lied to you, undermined the Constitution, started an unnecessary war, fired people in the legislative branch for political reasons, and has generally eroded everything America stands for to send it teetering on the brink of dictatorship. Support for this presidency is lower than low. So now is the time to exercise that well-preserved right to get your gun, march to the White House, and depose the tyrant.
Yeah, I didn't think so. Even if this were an advisable course of action, Secret Service snipers would take you out in 5 minutes flat. So you can throw that bullshit argument out the window as well.