Please be careful and start off by shooting something soft! My calcs show that, if the same materials were used, this spring will be considerably lighter than the original. I have been using the energy stored in the spring as the slide retracts as my figure of merit, and this one as you have described it falls about 20% short of the factory spring that the P64 came with. It COULD be made of stronger steel, but I wouldn't expect it to overcome that kind of geometrical disadvantage.
Saands
ps ... that HK spring must be SO close to fitting ... it is barely bigger than the PA63 at the large end ... maybe it rubs more toward the small end of the slide ???
Looking at Norm's photo of the two springs, one has coils
running to the left the other in the opposite direction, both at
a slightly different pitch & recoil has to be changed by these
factors.
Norm ... that certainly helps ... but even at 1.41" it looks like you will still be a little light with this one. The real difference in my calcs is the free length of the spring ... you are a couple of mm shorter than the factory spring I measured. It is AMAZING how sensitive springs are to slight changes!
I'll be interested to hear how it works ... and I think that I will hold off placing an order for springs until I build a spring rate tester so I can precisely quantify what we have and what we can get ... I should be able to get to that this weekend in the shop.
Norm, looks like by cutting off the extra length of the similar diameter PA-63 spring, you would negate any advantage of the swap. We just need a longer barrel. Think I heard that somewhere before. LOL.
JMHO,
Stan