Updated 11-25-14 (see new reply)
Equipment: 460XVR 8&3/8bbl w/ Nikon 2-8x EER SCOPE mounted on Weigand rail and Warne rings x2
Sequence of events:
Range session #1
• sighted in 25yd with commercial Hornady 200gr
• sighted 50yd w/Hornady comm 200gr
These rounds grouped around 1-1.5in.
• "Attempted" to sight in @50yd with handloads (300gr Hornady XTP MAG over IMR 4227 36,37,38,39gr in once fired Hornady brass COL 2.160 x 5rds each)
These grouped well but 8" and I was out of downward elevation adjustment!!!!
So, I go home and remove scope and remount, switching the rings front to back, back to front and bore sight it.

Range Session #2
• sight in at 25yd w/Hornady comm 200gr, groups well.
•"Attempt" to sight in handloads (same load as above except 38gr and COL 2.178) at 25yd
These grouped well, but 4.5" high (note this at 25yd)!!! One again, this is with using all available downward elevation adjustment!

The only fix I can think of is to shim up the front end of scope.
Any other observations, suggestions. I really need help guys; I am wanting to hunt with this thing this year. Thanks for your time.