Steel Case, berdan primed russian ammo. Non-reloadable. Some say the steel case causes excess wear on internal parts, though I highly doubt that the mild steel would be able to wear the steel in a quality modern firearm. The steel jacketed bullets do accelerate wear in the bore of the weapon however. The biggest problem with Wolf is poor obturation from the steel case. Failure to seal the chamber leads to carbon build up which can ultimately result in stuck cases and malfunctions.
I don't shoot wolf very often, but when I do, I clean the crap out of my weapons. Usually, boxer primed, brass cased ammo can be found in the same price range if you look hard enough. Even if you don't currently reload, you probably will at some point, so start saving brass now. JMHO
"The millions of people, armed in the holy cause of liberty, and in such a country as that which we possess, are invincible by any force which our enemy can send against us“ ...... Patrick Henry March 23, 1775