I've been reading that some people are replacing their springs with Wolf springs.
Some are under the impression that the weak factory spring is allowing the bolt carrier to slam into the seemingly harder G2 hammer and causing some mushrooming on the end of the bolt carrier. I'm having this problem myself with the mushrooming.
I'm not too worried at this point but the next time I need a gun part, I might throw a wolf spring into the order just for the heck of it.