BJT Saturation Design Point?
Read the datasheet more closely : there will be conditions attached to that spec for a minimum hFE. One of those conditions will be that Vce is greater than some voltage : probably 2V. (Just checked the datasheet; actually Vce=5V). When you are trying to saturate the transistor, those conditions obviously no longer apply. Instead, as Vce approaches Vce(sat) hFE decreases quite dramatically. 

Note that the actual base current and hFE will vary for Vce(sat) - you might find hFE=25 at that point for a particular transistor and a particular current Ic, or alternatively at hFE=10 you might see Vce lower than the rated Vce(sat) - the datasheet Figure 2 shows Vce(sat) around 0.05V for a useful range of currents! 
But these are the figures guaranteed by the makers for all their transistors.