Not many people leave high carbon steel firearms in the white because it rusts so easily. ”Rust” is another word for oxidize. Oxidize is is exactly what happens when something burns (just really fast oxidizing). The air and water vapor will rust metal unless you live in a desert, or have a dehumidifier in your safe, and even there it will still rust (just very slowly). Preventing oxygen from contacting the steel is the only way to stop rust. A layer of oil will do it.
That said, in all actuality browning or bluing is a very poor way to protect metal. Water on these finishes will still rust steel, so they require maintenance. Cerakote or a hot powder coating is a much better rust preventative on steel.
Problem is that for many of us a blued or browned firearm (centuries old technology) is beautiful, and cerakote looks like hot manure. Leaving your rifle in the white will mean you have to maintain and care for it a lot more than if it had a protective coating to prevent it from oxidizing. Most people don’t want that hassle, and the ones who really don’t want any maintenance use modern coatings. A white rifle won’t age well unless it is meticulously maintained. I have rifles in the back of safes I haven’t seen in years, but they’re blue, not in white, and oiled well before they’re put away.
You can certainly leave a rifle in the white, but you’ll have to pay a lot of attention to it, and if you don’t you shouldnt be surprised if the steel ends up rusty and pitted, even if you just store it.
