The cheap Russian stuff was and still is lacquered steel cases. They had to do that to prevent rust. And it will coat a gun's chamber when the barrel heats up after a few shots. Most shooters don't clean their guns immediately to remove the lacquer buildup after shooting stops. So the lacquer hardens and becomes almost impossible to remove without a jackhammer. It can be a beeotch to remove after it hardens. In the west we don't use lacquer, we plate the cases with a thin coat of brass or sometimes nickel.

Almost all shot shells are now steel rimmed bases with a coating of brass.