I don’t sweat what companies recommend or warn about regarding their barrels. Those warnings are geared towards the untrained and ignorant who mimic how to do things like clean a barrel and end up ruining their stuff because they don’t know what they’re doing. “The snipers use it so must I”…in my douchiest flabby nerd voice.
I have never heard of copper fouling issues because of a polished bore. It’s always been because a rougher or unbroken in bore, but whatever.
In the military long range precision shooting school I graduated from, we were trained to use bore paste, namely JB Bore Paste, during our cleaning process. The cleaning products issued were Shooters Choice bore solvent, Sweet’s 7.62 copper solvent, and JB Bore Paste. Bore polish was not used at every cleaning either. Deep clean, zero shifts, large round count shooting sessions, etc. Usually, if shooting say 500 rounds in a training session, we’d use polish after the end of the session. We’d clean each day but polish end of week or end of session, or something.
This could probably move to the rifle cleaning thread.