texagun said:
As I recall from my physics class, momentum is mass times velocity.
No argument. But my point is that it's not momentum that ignites primers, it's
power.
texagun said:
If you take too much mass off the hammer it will become unreliable
And I said as much -
if the hammer's
too light. A hammer that's simply lighter than factory doesn't necessarily qualify as
too light, though. A hammer's too light is when it's either unable to resist excessive internal friction, or it's below some mass at which it accelerates as fast as it's gonna accelerate. At this point, power drops off quickly.
boom boom said:
Think you want Kinetic Energy here which is 1/2 Mass X Velocity squared.
Nope. The hammer transfers the potential energy of the spring, and the above equation is only a way of determining how much energy is being transferred. It doesn't suggest the hammer's the source of that energy. The spring is the source of that energy, which can be calculated with a spring equation. And just because "mass" is in the equation doesn't mean KE goes down. Again, the energy comes from the spring, so if all you're doing is reducing mass, the spring's potential energy and the hammer's kinetic energy is unchanged, so velocity must go up. Power goes up because it's directly proportional to energy x velocity.
Here's an analogy for everyone: Consider a car rolling at 1mph into the back of yours. Your car's gonna rock a little bit, since momentum's good at moving things, but your bumper is likely ok. That's because the heavy slow car has little power.
Now consider some hooligan taking a whack at your bumper with a hammer. Same kinetic energy as the rolling car, but much less momentum, yet much more power. Your car doesn't rock as it gets hit because the hammer's got little momentum, but that hammer sure did a number on your bumper.
Power is what dent bumpers...and primers.
. A 10lb sledge will bash a hole in the wall, so you can eventually take a wall down with it. The framing hammer comes under the category of "too light". 
