HERE GOES NOTHING!!
The purpose of the wooden block is to prove-----beyond a shadow of a doubt, that I have no engineering education in my background whatsoever----NONE!! That is, except when I pop off like this and well meaning friends take pity on me and explain the real reason.
Okay---a little background: Each and every gun that came to live here got a bath---first class---came all apart (every single piece except for barrel and action studs on a gun like this), everything got soaked/scrubbed/rinsed and stuffed back together.
So there was this single shot, and when it got stuffed back together it didn't work---the hammer wouldn't go to full cock---the spring was too short. I began my diagnostic routine----sitting and staring. I finally noticed a little notch in the frame just a bit above the notch where the bottom of the mainspring goes---and where I'd put it. There wasn't anything else to do, so I took the spring out of where it belonged and put it where it didn't belong------in the little notch just above. Well everything worked fine, as light and smooth as silk, and it had a trigger pull to die for!!----way better than any of my regular single shots. I never did find out where that spring came from, but it was too short to fit in that single shot like it should, so they fixed things so it'd fit like it shouldn't----probably one of the first spring kits.
That brings us to this block of wood. It seems as though when you'd cock the hammer, the spring is going to bend from the top of the block----rather than from the notch in the frame down below. It seems like that would have the effect of shortening the effective length of the spring, decreasing the amount of leverage the spring had to overcome your thumb on the hammer----or your finger on the trigger if you were doing the double action thing----and making things lighter. And if that's the way it seems to me, then it probably works exactly opposite of what I said---so give it a try. See how it feels with the block in there---single and double action------and then see how it feels with the block gone-----and tell us what the difference is.
Ralph Tremaine