Here is something else to add to the mix. Some cylinders are harder than others. I have made about 8 22 cylinders into 32 cylinders. I have ran into 3 that were considerably harder than the rest. The one in my shop right now if the hardest of the lot.

The heat treatment a steel has gone through will effect how it blues and retains its color. I have put parts in the same tank at the same time and they do not all respond the same, some take longer, some I actually take out and dip in water to cool off, then wipe with fine steel wool and put them back in solution trying get them to match.