When I used to display guns on a gun rack, or in a glass covered case, I would polish the brass for show. But, for hunting, I always dulled the brass by using a bit of paste made from black Powder, and water, dipping a cleaning patch on it, and then rubbing the paste on the brass.
I Never have considered patina or shiney an " either/or " question. You can do them both.
Now, British troops were required to keep everything shiney, as they fought as Units,in ranks that fired volleys at their enemies, and then attacked the enemy with fixed bayonets. The Red Uniform coats, contrasted by the white pants, and vests, with the white straps across their chests, and all the shiney brass was considered a NOBLE and "in your face" presentation to the enemy, daring them to have enough courage to face the force, might, and courage of the British Army. This was a carry over from Medieval Fighting when Nobles were mounted on Horses, wearing polished armor, that announced to their enemies their status, their willingness to engage in physical combat, and their courage in the face of enemy soldiers. The Flashier the clothes, and armor, the better. It helped their Generals better see how the battle was going and who was gaining ground.
Once the rifle came on the scene, the ability of Britain's enemies to annihilate British forces before they could engage changed battle tactics, and, eventually, uniforms used. It was, sadly, NOT until the advent of machine guns in WWI that the Brits finally stopped sending their armies in human wave charges. Hundreds of thousands of British Soldiers were slaughtered needlessly, and it broke the British Empire. The Stalemate in that War only ended when Tanks were introduced to the battlefields, allowing crews to kill enemy machine gun crews fast enough that British( and American) forces could push the Germans back off the battlefields.
Today, It would be difficult to find any fighting force still using guns with shiny metal showing. "Shine" is something that belongs on sporting arms, for display, but poses some problems in the field, even when just hunting game. Yes, there have been plenty of deer taken with shiny guns. But, there also have been lots of deer lost to hunters with shiny guns because sunlight reflecting off the metal spooked the deer.
Still, its a personal choice. When guns spend 90% of the time in a gun rack, its silly to say one must NOT polish the brass on the gun. :hatsoff: