There's no way to answer that question adequately.
You have to make that determination yourself through examination.
Corrosion from corrosive primed ammunition depends on the amount of moisture in the air (humidity) to activate it.
If the ambient humidity is low enough, the corrosion won't happen. If it's high enough, it can happen very, very quickly.
The only way to adequately remove corrosive fouling is with hot soapy water. The soap removes any oil or grease that might be in the bore, and the hot water dissolves the fouling.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.