Unknown Metal Bracket Pieces... Military?

Probably obvious to someone. Got these today, grouped with a WWII German Ruptured Shell extracting tool for a mg34/mg42. Kinda doubt they are related, but who knows.

Two of them are marked 16, one is marked 20. The round piece looks like its marked C? 312(7?). Round piece measures 2 7/8 at it's widest point.

Thanks for looking.

 

thumb screws......??

 

Found a similar piece to the round one in this lot https://www.worthpoint.com/worthopedia/lot-used-vtg-clamp-mill-more-171576355 . Probably not anything interesting.

 

They are lathe dogs used to apply torque to a workpiece held between center points.

https://en.wikipedia.org/wiki/Lathe_dog

Dennis

 

Thanks.

 

Still sounds as if Torquemada might have employed them!