Find a magnet. If it sticks they are steel, and toss them. Actually, I already know you have steel, lacquered, to prevent rust. They are NOT reloadable, but do convert themselves to iron oxide in time.
Tula is the Russian equivalent of Winchester. They make ammo and components. The Evil Empire lacks copper and chrome, along with some other things. Brass is an alloy made with a lot of copper. Tula is a quality operation, and I bought 5 or 10 K of their 556 primers, when they were available, dirt cheap. I love them.
But, they sell mostly cheap bulk ammo in the US: Tula, Wolf, Bear, etc., steel casings, and usually steel jacketed, too. Same reason. My range, on National forest land, bans them, and the range master always has a magnet. You get your range fee back on your way out.