Pistol and Revolver “Main Spring”: Why is it called that? How does it work? 

Many times terminology is held over in our language from earlier times. We still “hang up” the phone even though it typically now just goes back into a pocket, and if we’re going to call someone we still “dial” them up even though the phone doesn’t have a dial anymore.
The main spring in a semiautomatic pistol is another such term that, for people who don’t have experience with revolvers, might seem a bit odd. The recoil spring is bigger and drives the action, so shouldn’t it be called the “main” spring?
In this video we look at why the term “main spring” is used for the spring which drives the hammer by looking at the SIG P210 and the Colt Python and how the term originated in revolver mechanics and makes perfect sense in that context.