Bringing this back up from the dead, but I remember looking at a thread where a similar bullet was shown (maybe just the base was similar). I think it was an 8mm Lebel? Don’t hold me to it, it might not have been an 8mm, but that thread might bring up an answer. I’ll look for it later.
AH! Here we are:
I’ll try a reverse image search in a bit. Wont be home for a few hours.