Hello! The "default damage" material is a mask, and not meant as a material. Everything under the "masking patterns" category have only an albedo input and are meant to use with Dynamask :) .
I don't think the scratches would be white... Also i think there would be be more damage around the magwell or hammer than at the front end of the slide.
think Im done with the highpoly modelling :) now to do the rest in Zbrush, adding some wear and damage. I think it will be really fun texturing this guy!