Hello Joe
I have a Model B (in 7x57, on a transitional intermediate action) with the fore-end that you describe, mine dates from 1910 and I surmise that it was something of a fashion of that era as I don't see it pictured in my 1930's reproduction catalog. Mine also has a rounded pistol grip without a cap.
The other main variation of that original price range of the Model B patterns was a fixed sight with folding leaves or tangent sight.
The point being that the model you describe is less often encountered and so has something of a rarity value for collectors.
