If you can find it, 3-in-1 do a "tool cleaner" spray can. This is the number one best carbon remover I have ever used for cleaning ARs. Mitre 10 used to stock it but I don't think it was a big seller. I tried to buy a case of it but can't get it.
CRC Contact cleaner is the next best but poorer substitute. I bought a case of this and use it as a post barrel scrub flush to waste for the barrel and gas tube, then air blow the gas tube and oil the barrel. It's not as harsh as break cleaner.
Same process for the BCG.
Once a year I throw all my bolts into the ultrasonic cleaner, bolt actions as well.
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