Have owned all the Big 60 scopes including the BSA big 60.
BSA big 60 cross hairs with centre mill dot.With black turrets.
Mk 1 big Nikko same as big BSA but with the option of mill dots or Nato ret.With black turrets.
Mk 2 big Nikko same as big BSA but with the option of mill dots or Nato ret.With small green turrets.
Mk 3 big Nikko shorter and lighter than all previous models with an additional lense also large green turrets and screw on turret covers.
The sidewheel works in the opposite direction to all previous models.
I have 2 of the latest models fitted to my 2 EV2 mk2 rifles and find them an excellent scope.
Are they better than the older models for range finding i think maybe there is nothing to choose betweem them.
I suppose the biggest advantage is they are shorter and lighter.
But at £600 each are they better than £300 for a good 2nd hand older model i dont know.
Hope the above is some help when buying a Big Nikko scope.
(Hereward FT club) Peterborough,Cambs.
The impossible is done right away,miracles take a little longer