I have one of these on my LaRue 20 OBR, mounted in a LaRue LT104 (the OBR has a 20moa cant built into the rail), it holds zero from Mass (my home) to Arizona and back! We hit out to 550 or 600(?) on the range easy, would guess that 800-1000 is possible. Great glass. I have the illuminated TMR. http://www.opticsplanet.com/leupold-mark-4-4-5-14x50mm-lr-t-m1-illuminated-reticle-metric-rifle-scope.html