Very interested in this project poodle..... Have one that has been on house gun duty for a very long time and as you say, spring rates are horrific.
Very much needed refinement and tuning .
Great project I HAVE to follow... Thanks !
Stay safe !
Tell me a bit more about your Walther, so I can see how closely our two projects track. Right now, my first bit of tuning will be galling, and the extremely tight machined fit. Even though it's almost all investment-cast (Ruger built an empire on that), the cleanup was very well done, and the fit is almost airtight. If you don't know what you're looking for, you'd never find it.
Out-of-the-box trigger pull is 12 and six pounds, not great, but comparable to most commercial DA pistols. That gave me hope, but it was that first group, and the comfortable shooting, that convinced me. One of the salesman will be bringing in his Walther PP in .380, because he says that one kicks like a miniature mule. One working hypothesis is that by cutting off some barrel, slide, and frame, the center of gravity has been moved down and to the rear, closer to the center of the hand. Even just holding a comparable PPK/S in the store, the PPK sat better in the hand.
I'll experiment with spring weights until I get something that is barely 100% reliable, then up everything by one pound. My rule of thumb says that change of one pound of spring rate yields about a half-pound change at the trigger. But it also lessens all the different vibrations and off-axis forces that are always bouncing around in a weapon. Those are invisible thieves of comfortable and accurate shooting, IMHO.