How about this one... could it be a proof? It looks quite a bit different from the others. The bottom part of Lincoln's portrait slopes gradually downwards to the fields, instead of abruptly tapering down. The rim look wide and square. The fields appear matte.
Extraordinary claims require extraordinary proof, but your coin looks very interesting. I'm leaning towards No. The rims don't seem to be squared off with the fields, especially in the 9 o'clock to 1 o'clock area. It's only my opinion and would not be surprised if I'm wrong, but based on the research presented so far, I think you have a nice business strike
Also, I'm guessing that Wikipedia's 1917 proof mintage figure of 1 is Breen's example (?). NGC and PCGS don't report grading any in the past. https://en.wikipedia.org/wiki/Lincoln_cent_mintage_figures
I just purchased it, so I'll have to wait and find out what it looks like in-person, and take more pictures.
By the way, what precedes the table shown in the first post is this message at the bottom of the previous page on page 30 (first pic below). So, the table refers to sales in 2017 of proof coins. The Mint also reports on page 10 the sales figures for proof coins sold, so it appears that the proof coins weren't melted (last image). Did someone purchase and hoard all of the proof coins, and pass away without telling anyone where it was??
OK here's the 1917 Lincoln cent - the hair seems to have a lot of details though this is normal among Wheat cents of this year. The right side of the coat appears to be sharper and is in very high relief. It looks different overall. The coin also appears to have an old cleaning, but the details still stand out sharply. Sharp square rims, no discernible die deterioration. The reverse is just as sharp. Currently the coin is stuck in a metal holder and I'm trying to cautiously take it out.
The sheen of the edge is also noticeably brighter than the matte looking obverse/reverse. I think that you can tell from the previous photos. Also, as an aside, I read an article that said that many collectors at the time hated matte proof coins because they lacked the appeal of a mirrored surface. So, they ended up spending them and putting them back into circulation! How many MPLs are in circulation, not to mention the matte proof Buffaloes?!
That part of the rim has the MPL look, but so do millions of Lincolns struck for circulation. The side and inside edge also need to be short and 90˚ angles. Even then coins meant for circulation can have that look. My 1920-D has sharp edges but I know it isn't a proof.
Maybe 1917 cents don't often have this sharp edge/rim feature? Crossing fingers lol. Are there any diagnostic traits similar across all or many MPLs?
There are assorted coins up and down the years that probably have this type rim, probably mostly in the 1909-1929 range. There are a few diagnostics from the master that are common to other MPLs of various years. One that comes to mind in the diagonal die scratch in the C of CENTS. I'm not positive but it may also appear on coins struck for circulation. This does not appear in the 1909 VDB 1909 1910 1911 1912 1913 1914 1915 1916