One comment regarding the spike base brads on this piece...there are originals of these that are flatter ie. "less domed". There are also older brads that have a hat like profile like a "rest" symbol in musical notation. We also encounter screw post brads on older helmets and the prongs on more modern ones can be thinner in width than what we normally see.
On officer helmets, generally of war time manufacture (zinc fittings with gold wash) I have examples where they used spike base stars with thin split prongs instead of the usual screw posts and square nuts. So be aware fellow collectors, that there are a few variations out there that are totally correct and original. Brian