Maybe Schwing, Cody and Madis made up their own terminology. Seems more likely to me that Winchester internal records referred to "Skeet Grade", and that the guns in fact have the "grade" characteristics detailed by Schwing. After all, Cody reports what's on paper in those individual gun records. Makes more sense to me that the difference is the marketing guys making up their own sales-focused terminology for ads and catalogs.

Jay