FYI.... All new sniper weapon system optics in the Army are mil/mil. They may or may not have a secondary BDC line reference, but they are being taught using mil based adjustments.
The MK12 (SPR) was initially fielded with the Leupold 2.5-8x36mm. The Navy generally switched to the 2.5-10x Nightforce.
BDC's- let's keep in mind targets orientation and institutional knowledge. Humans are tall and narrow. Range errors are not as big as a deal compared to deer, which are wide but short top to bottom. The military did not understand. MOA and mils in 1986 when the M24 happened. We do now. Mil adjustments and mil reticles. Makes sense.
To the OP-
A fixed 6x is adequate for for big game. You do not need to worry about parallax with a good scope below 10x or so. Dial for range, hold for wind. This becomes exceedingly easier if your scope adjustment matches your your reticle- ie. mil reticle/ 1/10th mil adjustments.
