All the baby snappers I have caught (up to 1 1/2 inch shell) have had somewhat soft shells. I have also seen some improperly kept that had very soft shells-one 3-4 incher in a nature center had a shell that folded easier than a softshell-the shell bent depending on how the turtle was sitting in the tank.
I've never bothered to keep one long enough for it to grow, and have caught the big ones up to about 50 pounds(one was weighed at 52), just wondering how old, on average, snappers have to get before their shell is actually hard?