Picked this W.R. Case & Sons 6276 1/2 green bone Sleeveboard for $5 at a yard sale today. I think the 1/2 is cause it's scaled on 1/2

Got it soakin in liquid wrench because the back spring doesn't want to move much.
Any one want to donate some green bone from that era to a good case - I mean cause
Also can't find in my reference book from this era. Only see 1920 - 1940 Tested.