Just as every bullet has its billet — that is, just as every bullet fired will find its billet, or lodging-place — so too does each of today's figurative bullet expressions have a story of its own. Let's take aim at three such phrases.
Horror fiction enthusiasts know a silver bullet can rid the world of a blood-sucking vampire for eternity. Fans of the Lone Ranger know that the radio and television star shot silver bullets at his most fearsome foes. And folks who have followed the figurative trajectory of bullets know silver bullet has a sterling reputation as a byword for something that acts as a magical weapon; especially one that instantly solves a long-standing problem.

Patients awaiting surgery without anesthesia might have hoped for a silver bullet but instead they were given a bullet to bite. That practice inspired the figurative sense of bite the bullet that means to enter with resignation upon a difficult or distressing course of action.

It doesn't have anything to do with anesthesia, but medical lingo does include a so-called magic bullet. That term is used for a substance or therapy which is able to destroy pathogenic agents without damaging side effects. The magic involved? Such protocols are rare and pretty much limited to antibiotics such as penicillin.