I think ANACS got the 15- correct also. As for the 17-, I can buy the AU, but I think it has been cleaned.
I will say they stayed the same. Not too sure about the 1917 since I never really graded or looked at them.
1915 - From 58 down to 55... certainly within the range what warrants consistency... just wish it could have made the AU63 jump. This was the the second one of the batch that I sent in where i was hoping for the Au63 bump.. got neither of them. Lesson learned. 1917Ty1 - From 50 up to 53.. same same imo.. not much difference between those grades. I tend to agree with the 53.. and am happy to have this coin in the NGC holder. Has a bit of that old dipped and retoned feel to it... but it is not as bright white as the picture represents as the pic was taken under a flash,, which tend to really make silver look white. A nice type coin for the collection.
I can see the 55 on the 1915. The beards are usually very nice on these with no rub on an MS coin. I can also see a little on the lapel, cheek and hair above the ear.