My backordered Wolfe 'Extra Power' recoil springs
[and firing pin spring] came today. I whipped up a comparison with my original (as the gun came) recoil springs, and the Wolfe 'standard' spring pack.
Because my spring gauge only reads up to 20#, and the two spring sets I compared last time both came in at 19# at full recoil, I marked off a line one inch into the recoil (approximately at halfway position) to make my comparison. Pics show no load and load at one inch.
I also measured my springs. The way I did it was to slide a razor blade into the first coil and count the number of turns. I counted the ground compressed coil at each end as one coil (or the fraction). I didn't bother measuring free length.
Here's my results. They are only valid for my own setup. It is apparent that the Wolfe 'Xtra Power' spring set is a higher pull weight than their 'standard' set. I can't make any assumption for the original springs, as I have no idea if they are WW II vintage or not.
Why have both sets of Wolfe springs??? Because I tailor my loads to my pistol. I'll load up an 8mm Nambu 'target' load and fire it with the stronger of the two spring sets. If it won't cycle, I'll reduce the load. If it still won't cycle, then I'll go to the standard spring set and the reduced load and work from there.
I don't trust the Wolfe 'standard' spring set. If my old original spring set is of WW II vintage, then it should be substantially weaker than the new Wolfe 'standard' set. My observations are that the Wolfe is the same pull weight as the original. That just does not seem right. Unless my original springs are replacements.