I wasnt refering to the grease or tenifer or black matt coating, the safety plunger and other parts have a mat gray coating on them,in older glocks it was black,then it was nickel plating and would routinely peel off,now it stays on a little better but does wear off after some use or polishing.
I dont know the metalurgy involved,Glock doesnt talk about it in its armorer schools either,but It appears to be a teflon coating over nickel , or teflon over tenifer. Anyway Im not saying polishing it hurts anything ,Im just saying glock as a normal routine wont replace the internals ,if they can tell they have been polished, or messed with,heck they wouldnt replace the nickel ones that peeled by normal use for some departments. I just wanted folks to know that, most gun companies are the same ,in alot of instances.But small parts are cheap,I polish up parts also.RB