I'm planning to shoot some local Gas Gun matches. Max range 700 yards. I have a NF SHV FFP Mil/Mil mounted on a .223 AR-15. I'm planning to hold over rather than dial. What's a recommended "Zero" and why?
If you zero at 300 yards then you won't be holding under more than 1 MIL at closer distances, and your 400, 500, 600 will fall very close to the whole MIL marks on the lower portion of the reticle.
I personally find it easier to hold in one direction (hold over for everything, instead of under for some and under for others). So I always just use 100 yd and hold over.
100 yards because conditions don't come into play enough to make much of a difference and you can find ranges or property much easier to confirm a 100 yard zero than anything further.