Thanks for the responses, and yeah, I plan to set it up more for "HD/duty" use, so I want reliability. As I understand it, going too heavy may cause shells not to eject property and/or stress the barrel lugs too much, so there has to be a happy medium.
I called STI and they said the gun ships with a 10# recoil spring and 15# mainspring.
15# mainspring sounds a bit light to me. I'm thinking about starting off with a 17# mainspring and a 12# recoil spring. Does that sound like a good starting point? and if that doesn't work out, go back down to a 10# recoil spring.
Oh and one other question, generally speaking, assuming the same powder loads, if I'm going from 115gr to something heavy like 147gr hollowpoints, do you generally want a heavier or lighter recoil spring with heavier bullets?
Thanks,
Brandon