This issue is quite common in Mint State from the many rolls that were set aside at the time, but finding a truly gem specimen is quite challenging. This is especially true if one is seeking a coin from fresh dies and having a sharp strike. Most 1940 S nickels were poorly made from tired dies having obvious signs of heavy erosion. Also common are ones showing die-clash marks or the excessive polishing of the dies to remove such marks. Combined with often sub-par luster, these condition did not make for attractive coins. This is an issue that will require very careful shopping. Despite all of these caveats, the sheer number of surviving Mint State pieces has resulted in a fair number of coins certified as having either 5FS or 6FS.