Been cleaning my blackpowder guns with Windex with vinegar for a long time; that includes my antique Winchesters. Never, ever had a problem with rust. After using Windex with vinegar and swabbing the bore dry, i give the bore a coat of Pro-Tec. The surfaces of the gun are wiped with a rag moist with MiliTec 1, Rem Oil or 3 In One oil.