quarantine 'em

It is possible that "S. W." indicates "Smith & Wesson", Grampa's gun which is seen earlier, and to which numerous characters have access - but only one shot was heard, and we already ruled this firearm out, above.

At this point in The Simpsons' run, there are several characters who definitely had these initials (and who appeared in this episode): * Waylon Smithers * Marge Simpson * Moe Szyslak (his surname was revealed for the first time in this episode) * ...

* Principal W. Seymour Skinner (first initial revealed for the first and only time in this episode) * Sideshow Mel * Santa's Little Helper (whom Burns refers to as "Simpson mutt" earlier in the episode) * Maggie Simpson

Still with me here? * Smithers has a cast-iron alibi - he was watching "Pardon My Zinger" at 3pm * Marge is on camera at the time of the shooting. This is enough for us as viewers * Sideshow Mel's weapon of choice is a flick-knife, which potentially rules him out as a shooter

Now let's re-examine the town hall seen. "Oh, you all talk big," Burns says, "but who here has the guts to stop me?"

So. If we've settled on Burns being shot with his own weapon, the "I think you'd better drop it..." dialogue is puzzling. What, if not a gun, was the assailant carrying, and why did Burns want them to drop it?

Earlier in the episode we saw Burns express his love for taking candy from a baby. Maggie's a baby, she must have had candy. The pieces fit!