I'm running a KKM barrel in my Glock 35. Never a problem with any of my reloads running. Some of my brass has certainly been fired in a stock Glock chamber. I use Dillon dies on a Dillon 550B. I do not use any special dies, because I haven't needed to.
My KKM is a drop-in spec barrel; any chance the one you have a gunsmith fit one?
It is quite possible its a match barrel.