I have a Keystone 25 yr.case that is to small for
an 18 size movement and to large for a 16 size
movement.I have tried several 18&16's in the case.
The front i.d.is 43.38mm and back i.d.41.19mm.
Could it be for a size 17?

Roger

Yes, possibly. If it is a later short stem case then it may be for the 17s Illinois Sangamo Special. Earlier long stemmed cases were used for the early first model Illinois "16" size and also for the Elgin "Convertible" 16s.

Thanks David,I did find a movt.that worked.16s.
Getty Grade 183 3 finger.

Regards
Roger