Well, that's a bummer. I haven't had a chance to try the heavy gripframe yet, but was going to try to Pro-Deal one to swap onto one of my 320s.
It isn't surprising that adding powdered W would significantly change the material properties of nylon. So that's a reasonable explanation, unless there's some mechanical interference with the slide somewhere.
I avoid 115 gr 9mm for multiple reasons, but a Production gun should be able to shoot any bullet weight reliably.