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Different firing pin springs?

I have often wondered why the 500's and 590's have such thick heavy trigger springs? It is so thick and heavy, you pretty much can not depress it by hand.
I installed a mcarbo trigger/hammer spring on my 590 last year at some point, and then started getting a fail to fire every now and then. Eject the shell and there was a light strike. So I figured the lighter spring for the hammer was not enough to overcome the super heavy firing spring spring.
I ended up putting the original hammer spring back in.
I have continued to wonder why they have such a overly strong firing pin spring.
I noticed on my 930, the firing pin and spring are a completely different design, but the spring is what I would consider a more normal weight. I can depress it by hand with no issue and it is not overly stiff.

Well I just recently bought a "parts kit" for a older 500ATP (Bought it for the stock). I was cleaning the parts of the kit and found the firing pin spring in it is was smaller diameter coils and I could depress the firing pin with no problem.
I remove it and the firing pin is a different profile than the one in my 590, but they interchange just fine. The spring from the old ATP was about twice as long, but significantly lighter weight.
So now I am wondering why did they switch to the current stiff spring?
I know the point of the spring is to prevent slam fires and make it drop safe, so having it in there is a good thing. But if the semi auto 930 has a spring significantly lower power than the 500/590, I have to wonder why the 500's have such a heavy one.

For people who like pictures, here is the old style firing pin and spring. (long thin coil spring)

Here is the current firing pin and spring. (short thick coil spring)
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