The face die is correct for that identification but the backmark dates it. His button of mclilly is most likely from the 1880's and 90's with its high dome and is probably earlier than yours as the die is slightly different. I'd say it's a score to grab an early military button civil war or not. I like the look of the one you have more than his actually. I can shoot you a picture of what the button books say when I get home if you want. I picked up a small handful of post war state buttons on a trip to Montana once, I was very excited to see anything out there.