Quite frankly, I don't think HR1022 has much of a chance of becoming law during this session of congress (perhaps after '08, depending on how the election goes). I just don't think there are 60 votes for it in the Senate. Of course, gun control measures are highly sensitive to current news, one nasty shooting could change the equation quite quickly.

If you are concerned about it, I think it would make a lot more sense to pick up extra magazines (and perhaps a black rifle or two) than more ammo. HR1022 doesn't have anything to do with ammunition, but it will ban a broad spectrum of rifles suitable for personal defense, along with any magazine over ten rounds. So if you've got your eye on an AR or AK, or if you have one already but don't have a good (read: lifetime) supply of magazines, now would be a good time to buy.