I have an old Winchester 1894 rifle with a hexagon barrel. All the metal on it is an even brown colour almost as if it is a brown bluing but I can't believe it wasn't originally blue. I know of the previous history dating back about 65 years and it wouldn't have been colour changed in that time. Is it just an even coating of rust from hanging on the wall for all those years and more? How can I tell for sure? If rust, and it is so even, should I attempt to remove it or leave it be?