Hmmm... First time I've heard that. I just checked my pocket change, and found five nickels with "full steps", and they were definately not "mint state".
Full step nickels are very hard to come by. You may want to check those nickels under a 10x loupe. The newer nickels must have 6 full complete steps with no nicks or breaks all the way across. Any waiver off of this standard will not get the FS designation. Earlier nickels only need 5 full steps.
I think there is a bit of a misunderstanding here about the original question. The grading companies only apply the FS designation to business strike coins. To the best of my knoweldge they do not use the designation when grading Proof coins. As for whether or not a coin has to be Mint State in order to receive the designation is another matter. Personally I cannot recall ever seeing a graded coin with the FS designation that was not MS - but that does not mean it is impossible.
Yep, 6 full steps with no nicks or breaks all the way across. Sorry, but I can't agree that they are hard to come by or that only mint state coins have full steps.
I have only found a few FS and a few of them are at NGC right now....I hope they agree with me!!! Speedy
