Ryan,
my understanding of the original observation was that it was about force, irrespective of travel, weight , etc..
Yes but, we cant separate force and travel. The force in a spring = k*x. The potential energy stored in a spring = 1/2*k*x^2. The question is really, why so much k in a break gun?
The break gun uses a relatively big k with a relatively small x. The auto uses a relatively small k with a relatively big x. The energy released is probably equivalent.
Thinking in terms of force is inadequate for explaining mechanisms. I find it easier to think in terms of work and energy.
