Skip ahead to 4:50 for the key bit. He knows that he’ll be primaried in 2012, so there are only three possible explanations for this. One: He’s already decided to retire and is thus emboldened to push whatever policies he likes. In that case, why not announce it a la Kay Bailey Hutchison? Put your vote up for grabs and extract whatever price you can. Two: He’s totally confident that any tea-party challenge is doomed to fail. Er, okay, but Bob Bennett was “totally confident” at one point too. Three: He cares enough about this issue that he’s willing to put his career on the line for it. Granted, there’s public support for some of the provisions of the old Assault Weapons Ban, like banning the sort of “high-capacity magazine” that Loughner used, but the AWB doesn’t have a prayer of passing with the new GOP House — as Lugar himself acknowledges. Why antagonize your constituents by taking a position that doesn’t stand a chance of becoming policy?

As for whether the AWB would have stopped Loughner, that’s an open question. Even under the ban, existing inventories of high-capacity magazines were still perfectly legal to buy and sell (in fact, HCMs were used during the Columbine massacre, which occurred during the ban), and Cho Seung Hui carried off the Virginia Tech massacre with 15-round clips, not the 33-shot magazine used by Loughner, by using multiple weapons. As Tom Coburn said yesterday, the problem here isn’t the number of rounds in the clip, it’s the fact that a palpable lunatic was somehow able to buy a gun legally. How you fix that problem with an elegant solution, though — a mandatory psychiatric evaluation for all gun purchasers is unlikely, especially given the cost — I don’t know.