https://www.milsurps.com/images/impo...er20pack-1.jpg
Am I understanding the markings correctly, “S57” indicates the en bloc was made by Sterling in 1957 and the axis pins, “F57” were made in the same year at Fazakerley?
This is the first one I’ve come across with an “S—“ marking. All the others I’ve seen didn’t have it. I wonder how the pins found their way into the en bloc.