This 9mm ammo may appear to be brass-cased at first glance, but look closer and you will see that it actually has bimetal cases. These are nearly entirely made out of steel, which is Wolf’s style because steel is far more affordable than solid brass. On the exterior the steel cases are copper-washed. This helps them feed a little more freely, and it also provides some protection against corrosion. But be certain: This ammo’s cases are not reloadable, and they’ll lead to more fouling of the action than brass cases would have.