Mystery gun ID - double feature!

[Ian]

All right, I've tonight I've got two new mystery guns for you to identify, if you're good enough. Last week's challenge was solved way too quick, so I've tried to find some trickier items this time.

This first one is a Sten, clearly. The question is, what is special about it? There's enough info in the photo to tell, I assure you. FWIW, it's a registered NFA piece with the happy switch, and I was fondling it all evening while hanging out at its owner's house.



The second one here is interesting for it's internal workings. This one doesn't belong to my collector friend, it was taken in a European arms museum. Not exactly run of the mill, eh? So the question is, what the heck is it?