Hi all,
I'd be interested to learn about this eatly "half moon" connector. I did once have a Mk3C helmet with a grey pigtail lead and small silver LEMO plug (about half the length of modern ones, with no flexible strain relief). It had 50% male and 50% female contacts, very fine pins, is this what you are referring to?
Adaptors - I have a LEMO to NATO adaptor as described. It's interesting to hear it's cleared for ground use only as I had been led to believe it was for the NBC intercom box, which has NATO sockets and is only used on the ground. So these two thoughts do tie up.
Cheers, Scott