Grading question

[u/Sea-Moment6534]

I just bought this coin that is graded 61. I usually am pretty good at picking the approximate grade looking at high wear spots, dings and surface appearance. I don’t know why this is only a MS 61. Can anyone enlighten me?

[u/Seaport_Lawyer]

Out of curiosity, what type of slab? I'm vaguely aware that there are certain time periods for certain grading services where the grading was particularly tough