From an opinion piece in The Economist, Apr. 21, 2007:

[The Virginia Tech killer] had two guns: a Glock 9mm and a Walther P22. Both are semi-automatic: they fire bullets as quickly as you can keep pulling the trigger.

Actually, the other dominant form of handgun -- a double-action revolver -- also fires bullets as quickly as you can keep pulling the trigger. The rate of fire from a revolver is, I'm told, slightly less than from a semiautomatic (I take it because in a revolver the trigger pull needs to do more than in a semiautomatic), but only slightly. One can certainly fire a revolver at least once a second with no extra training; it's not a good idea, since one generally won't be accurate with a revolver when firing rapidly, but one generally won't be accurate with a semiautomatic when firing rapidly, either.

Certainly for someone who is shooting at unarmed targets, and thus doesn't have to shoot several times a second -- and apparently the Virginia Tech killer was shooting at a relatively leisurely pace -- the difference between revolver rate of fire and semi-automatic rate of fire is negligible. (The difference in time to reload might be more significant in some situations, though again not in this one.)

Why does this matter? One common argument made by some gun control proponents, expressly or implicitly, is that they're just proposing modest restrictions on just a few guns. After all, it's politically easier to ban something that fewer people own than something that more people own. We're not trying to ban all guns, just so-called "assault weapons." We're not trying to ban all guns, just semiautomatics. We're not trying to ban all guns, just large-capacity magazines. And in the process of making such proposals, they have to explain why this particular kind of gun or magazine is especially deadly.

The trouble is that "assault weapons" aren't really materially deadlier than unbanned non-assault-weapons. Semiautomatic handguns aren't really materially faster-firing than revolvers. Bans on over-10-round magazines will almost never limit criminals, especially the sort of mass killers whom the gun control advocates are discussing. The proposals will do virtually nothing to reduce crime; while I agree that they're not nearly as burdensome to law-abiding citizens as total gun bans would be, they also aren't burdensome to criminals. These modest proposals will fail. And what will gun control advocates propose then?

(More aggressive bans, such as total handgun bans or total gun bans, might actually have more of an effect, both for good and for ill. I think on balance the ill effects will exceed the good ones, but that's a separate matter; at least there's something more than pure symbolism or misunderstanding behind them.)