The earliest R Grades were engraved with that bit of scroll like you usually see on the S Grades. About when the S Grade came out, ca. 1908, the R Grade engraving changed to a single dog looking up at a single bird on each side. If yours is marked R, it's an R. The R Grades came with Damascus or Krupp barrels, while the S came with Flui-Tempered [fluid] steel barrels.

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