by Wolverine Wed Oct 28, 2015 5:40 pm
My guess would be that first pattern liners were replaced as they wore out, but otherwise remained in service alongside the later style helmets and liners. Most of the rivet-less helmets I have handled appear totally unissued, although I doubt that tells us very much. When all of these NVA helmets first became widely available in the early 1990s, I was buying them really without paying attention to the liners. The going rate in my neck of the woods was rarely more than $15 at the time. One of the first ones I picked up had the early style liner, but I only appreciated its relative scarcity much later on.
Also, I have found quite a few helmets where the rivets, while present, no longer serve any purpose, since they are fitted with the later style liners. These shells still have early dates, but who knows when exactly they were reworked...