Assuming that a lightsaber is a magnetically-contained tube of plasma (although theories are abound as to how this is achieved) and the typical bullet is made of either lead or copper-jacketed lead, how would said bullet interact with a lightsaber?
I've heard two possible theories on the outcome:
- The bullet is heated to such temperatures that it turns to gas (i.e. vaporization). Would the temperature of the plasma be high enough that the short period of time that the bullet spends within the lightsaber blade be enough to melt then vaporize the metal? Considering the amount of time that Qui-Gon Jinn spends trying to pierce the bridge door in The Phantom Menace (and the fact that it appears that molten metal drips from the door), I am assuming this is unlikely.
- The plasma in the lightsaber blade is at a high enough temperature that the bullet melts and turns to liquid lead, but not so hot that the lead vaporizes. The Jedi (or Sith) proceeds to get liquid metal thrown in their face, accompanied by third-degree burns.
Evidence from the Phantom Menace can be discredited by the fact that the bridge doors were most likely composed of durasteel rather than lead or copper. Durasteel "is capable of withstanding blistering heat, frigid cold, and monumental physical stress."
Note: I have read little to none of the Expanded Universe, so I apologize if the question is successfully answered in one of the EU media.