I’m in that group. The gentleman has an amazing collection of camos. He said this is wartime period since the black line next to the emblem was painted over it. Also, there’s another helmet that has this exact emblem painted with a camouflage pattern
I've seen a similar helmet or maybe it was the same one with identical insignia, posted on a forum some time ago. Can't remember which forum, but the upshot was no one had seen anything like it, or knew what it is.