Originally Posted by Don P
Spring pressure is what will make it go bang not hammer mass.
We're getting a little OT, but to clarify, spring tension per se
isn't what ignites primers, either. The spring stores the energy that the hammer delivers. Put in a heavier or lighter hammer, and delivered energy is the same.
is what ignites primers, and power is that energy per unit time. Though it's lighter and has less momentum, the lighter hammer travels faster, so delivers a more powerful strike. For instance, compared to a sledge hammer being swung, a car rolling at 1mph has 10 times the momentum, but the same energy. Yet the the sledge will deliver 10 times
the power of the car, which is why it'll certainly affect your bumper more.
One advantage of a lighter hammer, then, is that you can run lighter springs while still delivering enough power to ignite primers reliably. Another advantage is the reduced momentum jars the muzzle less upon hammer strike. Combined with a shorter lock time, you can actually get an accuracy bonus by cutting that hammer down.