In Delhommes 'French Grenades of WW1' he shows a safety pin called the AP Ring Pin. I see these often on F1s. This is the only one I can recall seeing on a Mills (aluminum plug, M&Co. 11/16). Any of you see these on the Mills befor? It seems like a practical safety pin that is easy to use but maybe there were problems with it. Otherwise why didnt it become standard issue on other grenades in other countries?