Brass-Plated Steel heads for Shotshells is now just about the world wide industry standard (except for those who use unplated plain steel.)
I have recycled 100s of 1000s of Once-fired Euro cases, and except for the occasional "rust spots" at the forward edge of the metal, no problems ( cases fell onto dewy grass at club). Obviously the Clay Club members have no problems either, as they fire 100s of 1000s of (Euro) cases monthly here in Australia ( my usual collection from a single club is 30,000 to 50,000 cases a Month.) The Majority of cases are "European" ( Rieffenhauser) and with metal heads from very low, to very high, in Brass plated, Zinc plated and Nickel Plated steel. US cases we get in Plain Steel are Federal and some Remington and Winchester. Others are in brass-plated Steel...Winchester has not used pure Brass since the early 1980s.
RIO ( UEE now MAXAM) of Spain are High quality cvases (Thicker Tube), and the "Nobel" type made in Italy are also equivalent to Fiocchi etc.
One must remember that a lot of European "brands" are simply Case Fillers, and Buy in their Shells from large Makers of both Cases and Loaded ammo ( RIO, Fiocchi, are some of the Major Case and Loaded manufacturers) Even Winchester buys some of its shells from Italian Case Makers, and Eley (UK) buys from RIO. All the Aussie Shotshell fillers buy from Italy or Spain. (Shells, Primers and even Powders).