Quote Originally Posted by evert View Post
No stroke change. Just a spring that gives lower muzzle energy.
i didn;t say the stroke was changed

let's say all things are equall and you simply change the spring for one that gives lower ME...

what could have happened to give lower ME ?

Less spring energy - no clear affect on muzzle pressure
Slower spring acceleration, but more preload (softer spring) - this will reduce piston bounce, increasing air pressure in the barrel
heavier (weight) spring - will also reduce piston bounce, increasing air pressure in the barrel
slowing spring - reduces peak pressure, and muzzle energy, but also reduces piston bounce, so potentially more pressure at the muzzle on pellet exit (althouth lower peak pressure at pellet start)

There are so many variable, but the above are all possible explanations based on the limited knowledge I have.

Another way to look at it... ME is largely (but not only) correlated to peak pressure behind the pellet.
Muzzle crack is (almost totally ?) related to barrel pressure at the time of exit.

So how can you get lower pressure behind the pellet at start, but higher at muzzle exit ? Answer: piston bounce, which at it's most extreme sucks air back from the barrel, or at leastprevents the flow from the chamber. So any spring change that decreses piston bounce, can increase muzzle crack. FOr that same spring to also decrease ME, it only needs to have less energy. The two are not mutually exclusive.

HTH - JB