VP9s were in production for about 2 years I think with the 'old' red 9mm specific spring with no systemic problems except possibly shooting suppressed. I believe they switched to the silver .40 spring with the release of the tactical mostly as a logistics simplifying thing. I'm certainly not replacing the red RSA in my first VP9 just because. That said, the issue of failures with the stronger spring I was able to avoid in my VP9T by keeping the slide locked back over a couple nights. I suppose the longer barrel might also make a difference. I even shot Tula out of it on the first outing with no stoppages.