The vast majority of support discs are black especially on the issued OR's helmets. In fact, I have never seen an issue helmet with anything but a black tin disc. However, once we get into the world of private purchase officer, OYV or whatever, then we find differences. For example support discs made from aluminium. Cruciform supports also in aluminium and black painted tin. The Garde officer helme that I just finished restoring has a black tin disc but a piece has been cut off the circle so that it did not interfere with the nut and screw post which hold the top of the rear spine in place. I also worked on a superb pioneer officer helmet that had an aluminium cruciform support that had elongated arms so that essentially, the entire shell was supported. The front arm was held in place by a split brad that was hidden behind the wappen. The side arms were held by the chin scale brads and the rear arm by the rear spine screw post. Needless to say, with this amount of support, the helmet shell was in excellent condition. I believe I had to re stitch a visor on that one and put on a set of Randy's repro silver scales.
Hessen OR's helmets for those of you who have never held one have a large circular tin disc probably twice the size of the normal issue. The Hessen idea seems to have been to support the cruciform spike base with a larger disc. However, my Hessen reserve officer helmet has an aluminium cruciform spike support. Brian