My experence with Burris scopes has been very good.
here is an address that might answer some of your questions.
Burris - XTR
The 6x24x50 has all of the good stuff ( 30 mm tube with side focus,
posi lock,mil dot or ballistic mil dot and a stronger/heaver scope tube).
I recently installed a Burris on my 416 Buff and found the turrets dead
on and the posi lock has held the zero on in spite of recoil (60 ftlbs)
and around 200 rounds.
Thats about all I know about this scope.
J E CUSTOM