An e-mail:

The main reason we ban guns in the Capitol and House and Senate office buildings [is] that they’re assassins magnets. Generally speaking, no one of political importance is in your local restaurant or department store. But politicians are always in danger because of the nature of their work. As such, they are targets for everyone from kooks to terrorists, and when you get a bunch in one place you may as well paint a big target symbol on the building.
One could say the same for a gathering of Hollywood stars. I’d be ok with banning guns at the Oscars, and maybe they do.

Update: And another reader responds:

The thing your correspondent who notes the assassination angle fails to note is that a ban on guns in the Capitol is not likely to deter a would-be assassin. If someone is eager enough to attempt to take out a political figure, he or she will do so regardless of a weak ban on guns within the Capitol building. Especially since they seek to assassinate someone presumably in the presence of laws that ban assault, murder and assassination! Unfortunately, your correspondent trips over very common logical fallacies of the gun-banners.

Update II: And yet another:

Utah allows its citizens to carry their concealed weapons in the state Capitol, and no blood has flown down the aisles. In fact, I seem to remember that it was quite controversial when the SS would not let legislators pack guns when Cheney came to give a speech a few years ago.
The few places you can’t carry are jails, police stations, mental health facilities, airports and courthouses. All places with metal detectors. It is even legal to carry in grade schools, and for college students to carry to class.
That may seem crazy to some, but we have not had any problems.