Nikon scopes used to have just one line - Nikon. Then, Nikon came out with the Monarch UCCs and Buckmasters. The original Nikons (of which I own a few) are wonderful - clear, bright, and sharp, not to mention EXCELLENT tracking. Their light transmission was 88%.
What Nikon did was come out with the Monarch that has 95% light transmission (like the Elite 4200s). In any event, Nikon essentially used the glass that was in the original line and called it their "Buckmaster" line. Granted, the Buckmaster scope looks a bit different than the original Nikon line, but the glass is the same. However, I am not certain whether the scope integrity of the original line - which was passed to the Monarch line, was also passed to the Buckmaster line.
Zachary