Most military-issued firearms are worn out or damaged by excessive and/or improper cleaning. We should stop using the word "clean" and start using "maintain." A properly maintained firearm is NOT white glove clean.
Maintenance means keeping the mechanism functioning and preventing corrosion. Powder fouling ("carbon") does no harm and needs to be removed only so that it doesn't impede function. A use RBC (Rifle Bore Cleaner) or Hoppe's #9, brush the part, leave set for a few minutes and wipe off. This may not remove it all but will get enough carbon to remain functional. That is your goal.
It is counter productive to strip off all the carbon, especially if you are reduced to harsh solvents or unauthorized metallic scrapers. Light lubrication should remain to prevent wear and corrosion. Many lubricants have a mild detergent that will bring tiny amounts of fouling out of the metal's pores. Thus, a wipe of the finger will show residue. This is GOOD! It means there is lubricant protecting the metal.
Proper maintenance should take ten minutes, usually less.
Review the Technical Manual (or read for the first time) and confirm what I've written. If you don't have a TM handy Armalite published a report for AR-15 type rifles but it applies for nearly any military or civilian firearm.
So why are Soldiers and Marines suffering through extended cleaning sessions, stupidly scraping away parts and destroying perfectly good weapons in the process?
Personnel assigned in an armorer slot rarely are actual, trained armorers. Instead, the unit armorer is an NCO of sufficient rank to be entrusted with arms room keys and assigned an extra duty. In the Army, the person may be a 92Y (Unit Supply Specialist) so handling firearms is just another inventory task. And to top it off, even formally trained military armorers are more likely to be parts changers, not gunsmiths or marksmen.
The crime usually goes down like this. PVT Joe Snuffy is tasked to clean weapons. We'll pretend Joe actually bothered to read the TM (Technical Manual) and found that he only needs to brush and/or wipe away any obvious corruption, put a thin wipe of CLP over the metal surfaces and lightly lubricate the moving parts. In ten minutes he's performing a function check and ready for turn in.
SSG Clueless, the supply clerk with vault keys pretending to be the unit armorer, "inspects" the maintained weapon. Not really understanding what to look for he wipes his finger along an internal part and picks up a bit of CLP Joe put there to prevent rust and corrosion. "See here, this weapon is dirty. Clean it again."
This frustrates Joe and rightly so. This private actually glanced at the relevant TM within the past five years instantly making him more qualified than the "armorer." However, Clueless is four pay grades above Joe and in charge of the arms room, so Joe loses.
Joe swabs away on his already maintained weapon. He gets pipe cleaners, cotton swabs and starts into every little nook and cranny to clean everything. Thirty minutes later Clueless rejects it again.
Joe is annoyed and desperate and just wants the ordeal over. Determined to not come back a third time he is ready to strip the damn thing dry. Harsh degreasers, metal picks, solvent tank baths. Who cares if its not in the TM. Clueless won't take it unless it is really "clean."
An hour later Clueless does his white glove treatment. The bone dry, unpreserved, unlubricated parts have had any remaining protective finish scratched away. There is nothing there now but bare metal. Clueless seems content so Joe is happy.
And that is how the Army cleans guns, Joe learns. Years later, Joe reclasses as 92Y, is entrusted with the arms room and ready to pass on the "lessons" SSG Clueless taught him.