re: How to address rust issue on new Remington 870 Express Youth?

Chicken,
Congrats on taking your son to shoot his shotgun. Shouldn't be a big problem removing the rust. Sometime, a good clean, lubricate and protect oil (like CLP, found at Wal-Mart, or Eezox) will remove the oil by itself. If not, try a slurry of Mother's Mag Polish (I buy mine at O' Reilly's) or Flitz (I think it's available at WM) mixed w/ one of the above oils. If neither of those two work, use some VERY fine steel wool. For rust prevention, I recommend: CLP, Shooter's Choice Rust Prevention, Corrosion-X or Eezox). LOTS of ways to remove rust, but these are the ways I do it.

Be sure and take the gun apart and treat any hidden rust. Make a point of showing your son how to care for his equipment. He won't remember HOW you cleaned the gun, but he WILL remember you cleaned it.