Without this one particular component, a gun is actually nothing more than a revolver-shaped paperweight. However, according to a recent Pennsylvania Supreme Court ruling, MANDATORY SENTENCING ENHANCEMENTS apply since it meets the "legal" definition of a firearm. (Story HERE)
Chief Justice Robert Castille said that "firing a bullet is the only true ‘designed’ function — in fact, the essence — of a handgun, pistol or firearm." The Chief Justice is correct in this regard. However, he compares apples to oranges in his next statement. "A car without gas does not lose its identity as an entity designed for locomotion. A laptop computer does not cease to be a computer if its battery is removed. By the same reasoning, nor does a handgun lose its designed function merely because a critical piece is missing."
His analogies equate to a firearm with no bullets, not one missing a firing pin. The correct analogies in this case would be a car without an engine and a laptop without a CPU. Here in East Tennessee, Chief, a car without an engine is a LAWN ORNAMENT! And there is no way a laptop without a CPU can do anything but collect dust.
By the same reasoning, Chief, this little firing pin could also be twisted into being defined as a "firearm", since it's only purpose is to strike a cartridge's primer and fire a bullet.