Brit Sten Marks

[froster]

Is there much significance to the letters U and P on either side of the broad arrowhead at the back of the rear receiver ring just below the rear sight? Also, how many marks such as RTL can be found on the mag wells?

[froster]

As a further request for info on Stens, has anyone seen a barrel from a Long Branch Sten made for China with six grooves and an aparent Chinese character on the side that looks like a mushroom? I saw one and later drew the character for a Chinese guy who didn't recognize it, thinking instead that it was the math symbol pi. I wonder if these things are covered in any collectors' books.