The condition of the box looks far too good, for cardboard which is getting on for 100 years old? Also said condition is out of sync with the condition of the pistol which looks quite mediocre - either the box should be much tattier, or the pistol mint?

If you lifted the pistol from the box you would be able to tell in an instant whether that gun had lived in that box for all time, just by looking at the inevitable scuff marks inside?
Also as has been said already, the fact the gun is part disassembled is not a good sign of authenticity.
Apart from all that it looks great!