Semiconductor-grade cleanliness not necessary and not desirable
If this thread has restricted itself to the queston of whether patches should come out white or slightly gray, I say slightly gray. I knew this before reading the Armalite article.
I am professionally engaged in cleaning materials for either/both high vaccum use or to semiconductor-grade cleanliness (this latter is essentially "atomically clean". i.e., no foreign matter down to the atoms of the base material, the bore alloy). Some of the parts we clean arrive dripping with machining oil or have been sand-blasted to 40-60 grit roughness. Knowing what it takes to clean surfaces to such degrees (strong aqueous detergent, copious rinse with de-ionized, i.e., inherently corrosive, water, ultrasonic cleaning and more), I cringe at the thought of subjecting a firearm bore to such cleaning. In effect, the part has to be designed to be cleaning this way and the whole remainder of the assembly has to be designed at the same time to be compatible. None of this applies to gun barrels, throats, receiver parts, etc.
On the contrary, carbon/soot/graphite deposits (e.g., from partially burnt powder, bore oil, wadding, etc.) on the bore are lubricious and protective, in a sacrificial but renewable sense. Lead, transfer-rubbed off the bullet itself, is also a benefit. Copper from the bullet cladding is less good but still better than the bare steel. Chrome lining is good because chrome, as plated, is smoother and more lubricious than almost any bare steel surface, plus the plating, if applied thick enough, fills in the microscopic grooves from machining and polishing the bore. But not to worry. If you don't have plated chrome, the carbon, lead and copper will also fill these grooves preferentially.
Just drag a patch through the bore 'till it comes out light-gray and then apply you favorite rust-preventive finish oil or similar product. Your real enemy is hard particles, like sand or steel filings. These might scratch the bore when being dragged along by a bullet.
