My brother-in-law has a GP100 - unmodified - that would not reliably fire the reloads that we made with CCI primers - there would be an indentation in the primer, not quite what I'd call a light strike but definitely not as deep as it is on my .357s (which have always fired my ammo just fine). It hasn't misfired with any factory ammo but it definitely does not hit the primer quite as hard as it probably should. He didn't want to send the gun back, especially since it seems to fire factory ammo without any trouble - so we tried Winchester primers for his loads and they have been 100% reliable so far.
It would probably bother me enough to have it properly fixed at some point, but in the meantime it's worth trying another brand of primer if you can find some. Federals are generally believed to be the most sensitive, and Winchesters also seemed to work in our case.