Don't Shoot

Let me admit to some ignorance--I've never read The Three Musketeers.  But I've seen it on film.  Man have I seen it on film.  At least five versions.

So here's my question.  Where are the muskets?  For guys whose name is built around it, all they ever seem to do is fight with swords.

PS  It's called The Three Musketeers, but the main character is d'Artagnan, who joins the titular three (Athos, Porthos and Aramis, for those keeping score).

Wouldn't a better title be The Fourth Musketeer?

It may not seem like a big deal, but I once saw a guy lose a lot of money on Who Wants To Be A Millionaire because of this confusion.