It sure looks like it. It's even a clearer S than the one in the cherrypicker guide. The big things too make sure here is that the S wasn't added to a 1941. Especially since the place or person you got it from didn't notice it and the price just to 100-175 in unc. condition. Also you may want a dealer or someone in the know to check as I think I see extra metal under the middle curve of the S. It MAY be a large over small, an large S or large S or could just be an extra piece of metal or even glare from the photo.
Ya it's a nice coin and the mint mark is ok. I just went in and bought some rolls from him and found 8- 1941 Lg S Nickels.
Is it me or does the pic #3 look like the S is stamped into (IMPRESSED INTO) the metal instead of raised on the coin???
