As you all know, this subject is at best controversial. Some time back in an on-line search for testing on preservatives for gun steels I came across a product that was testied superior to RIG which has always been regarded as about the best in preserving steel, next to cosmoline. The product............. old -fashioned VASOLINE petrolem jelly.
Now, how to get a black powder bore really clean before storage....that has yet to be determined??? My best efforts have been with Ballistol and/or BreakFreeCLP after using very hot water and dish detergent. Before shooting, a clean patch and blue Windex gets it squeeky clean!
Jim