Rick, your gun has the Curtis for-end release and the "R" suffix is usually associated with these guns from 1912-1919. A great idea and a great way to keep the for-end on these early guns. Sometime after 1919 all grades from Ideal up that did not have ejectors had a roller release that held the for-end on the gun, the only one without it was the Field Grade. The Curtis was a great idea, Hunter Arms stated they stopped putting them on because of a patent infringement, but it was more of a cost factor as these took many man hours to fit.