The helmet doesn't have flat rivets because I don't believe it was used during World War I. This was a post-war reissue, and I believe occured in the late 1920s and 1930s. I don't know the reason and no source really explains the WHY, but it seems that Austrian and German helmets were suddenly sent to various nations about a decade after the end of the war. I wish I knew WHERE the helmets sat for 10+ years, but I just don't know.