This is my first ever reply here!
Your coin has the remnants of the S too large. In the OMM, it is shorter and more in the middle of the D. Try poking it with a toothpick and see if it is just dirt or actual metal. If it is metal it may be an unlisted RPM.
Your coin has the remnants of the S too large. In the OMM, it is shorter and more in the middle of the D. Try poking it with a toothpick and see if it is just dirt or actual metal. If it is metal it may be an unlisted RPM.

























the area close to Lincoln's chin (marked on the clarified OPs photo uploaded below)








