Happy to see that the UR13 topic has many fans, and allow having a look at other nice and rare tschapskas,
concerning my last purchase, I confirm that's a Unteroffizier private purchase, it's almost the same quality as an enlisted man piece, just slightly nicer, mainly the plate which finish is better (silvered "blanc de Berlin), while EM's are not silvered but plain nickel silver (maillechort in French), other remark that confirms the unter offizier option: the hand written rank + name Unoffz Schwamengel (?). It's Sütterlin but quite readable. Last remark, unteroffizier is some sort of sergeant, that's the first rank in NCOs, while other NCOs as Feldwebel or Vize feldwebel are almost considered as officers. The quality of their headgears can sometimes be close to the quality of Einjahrfreiwillige for instance. Also, to confirm that's a private purchase, the tschapska is not marked excepted for the maker mark + date, no reception mark. I have an EM one which is marked UR 13 and all other EM tschapskas are marked after the regiment.
Last last point, I did not get it on a flee market nor garage sales, but from a family who had inherited a big house full of old stuff... a grand father was a general (French) in WW1, a trophee presented to the general by his officers ?
my remark concerning the plate (UnOffz/EM), find here a pic of my EM tschapska plate, that's plain nickel silver (EM) while private purchase (Unoffz) is silver plated .... 
