Please refresh my memory on microns. Is that .0001 meter = .1 mm, or .00001 meter = .01 mm, or .000001 meter = .001 mm?
"Penetrating" the metal sounds like what's been called carburizing (sp!), done on USGI M1 & M14 receivers. That's definitely on the "hard" side of life. But the thickness described is like nitride, isn't it?
The Glock barrels I've looked at appear quite smooth and slick inside...