To each his own, but my personal experience with case colors: leave them alone. Protective varnish of any kind can peel, and when it does, the case colors go with it. It ain't pretty.
If you use a gun, it gets wear, everywhere. Don't worry about case colors getting worn off as you use your piece. It looks right. And I learned a long time ago to NOT handle the receiver with sweaty, dirty hands, or clean ones for that matter, when handling or carrying.
If it's a safe queen collectable, just keep it away from the sunlight, lightly oiled.
JR