If I lived on the frontier in the time period of your persona, I personally think one of the last things I would have time to do is polish brass on my Rifle Gun. Even in winter and at night, there are other things a bachelor would have had to have done.
I am not sure if my next point would have mattered to your persona, but I think it would. I would not want something that shiny to give away my position to either hostile European Immigrants or Native Americans. For the most part, anything that shines in the woods is alien to the woods. Actually, I think I would have used vinegar, some types of foliage, or something else to make the brass less shiny ”“ especially in winter when there is less foliage to cover something shining in the woods.
Now, MAYBE I might shine the brass if it was for the Quarterly Militia Assembly inspection. However, I doubt that would have made the gun “unserviceable” if the brass was not shined and caused me to be fined. In one Virginia Militia Assembly during the period, the Inspector found Corn in barrel of one Militia Man’s Gun. Though I’m sure he was read the riot act or at least caused to be the butt of some scorn and/or ridicule, the quote didn’t mention he was fined.
Gus