1. My first preference in rings is Burris Signature Rings with the Posi-Align inserts
http://www.burrisoptics.com/sigrings1.html. These provide secure mounting (even on heavy recoil rifles); do not mar the scope finish; can compensate for imperfect mounting hole to barrel alignment; compensate for misalignment the rings (without reaming or lapping the rings); and can be used to provide the equivalent of a tapered mount tilt for long range shooting to keep the scope adjustments in the preferred close to center for least distortion.
2. I have two fixed power March scopes, 50x and 60x. Based on initial testing and a partial season of use I can report the following:
Image quality is fantastic - sharp and clear to edge of field with near perfect color correction.
Resolution - slightly beats calculated Dawes Limit on AF resolution target - easily resolves 6mm and .224 bullet holes on both white and blue portions of IBS target at 600 yards (even with light mirage) - will resolve 50% overlap pair of 6mm and 30% overlap pair of .224 holes at 600 yards with no to low mirage.
Brightness - even with small exit pupils (1.04mm for 50x and 0.87mm for 60x) - the perceived brightness is as good for the 50x and just slightly less for the 60x than my Weaver T36 (1.11mm at 36x) in side by side comparison - the Marches will both provide useful target images to about 30 minutes past sunset.
Parallax/focus - even though I favor objective focus, both scopes show backlash free and solid settings and are remarkably accurate relative to the turret markings.
POA adjustments - 72 MOA elevation and 50 MOA windage - 1/8 MOA actual and no perceptible linearity drop off to within 5 MOA of limits - repeatability is as perfect as I can measure - no detectable shift under recoil or handling.
CAUTION !
Many that are not experienced with using high power (>27x) diffraction limited (by objective size) resolution optics compare their visual perception of images from lower power (<27x) optics where resolution is limited by the users visual acuity. Typically, such users report a perception of lower image quality from the high power scopes.
The problem arises because the eye-brain visual system has adapted to its acuity limit by essentially filtering out (ignoring) any image detail below the acuity limit. When the optic quality is good enough to be diffraction limited and the magnification is high enough to make your visual acuity limit better than the diffraction limit, two effects occur: increasing magnification adds no additional visible detail (although visible objects get bigger and occupy a larger portion of the field of view) and increasing magnification will show (for visible objects) more of the diffraction effects (fringing of edges due to optical interference) which are perceived by inexperienced users as blurry objects or edges.
As with most tasks, with sufficient practice you can adapt and train your eye-brain visual system to correctly perceive high magnification diffraction limited images and better analyze the magnified small field of view with larger objects of interest (bullet holes) less extraneous clutter (other targets).
