I did some math to figure out if I wanted a 0 or 20 MOA mount for the ATACR 4-16 with MIL XT on my 5.56 rifle shoting 77 grain open tip match rounds.
I came to the conclusion that a 0 MOA base would give you better optical quality at your 100 yard zero, which you could then hold for shots out to 600 yards (which is most all I'll ever shoot).
Is it feasible to hold to 600 yards with the MIL XT reticle on a 5.56 (requires about a 5 MIL hold)?
The math and reasoning:
The internet tells me you need about 4.5 MOA elevation for a 100 yard 5.56 zero. So with a 20 MOA base, you'd actually have to dial down (from center of elevation adjustment) -15.5 MOA to zero at 100 yards = worse optical quality @ 100 yard zero.
With a 0 MOA mount, your 100 yard zero would only be deviated from center +4.5 MOA (+1.3 MIL) = better optical quality @ 100 yard zero.
A 5 mil hold (which I assume is feasible on the Mil XT reticle?) will get you past 600 yards. So, with a 0 MOA mount you will have better optical quality holding to 600 yards than a 20 MOA mount. You would have to dial the 20 MOA mount all the way out to 500 yards to get the same optical quality as the the 0 MOA mount @ 100 yards, and dialed to 500-~700 yards, would have better optical quality.
So for shots out to ~600 yards using a MIL XT reticle, a 0 MOA mount will give you the best optical quality (which will be most of my shooting). The remaining 11.7 MIL of available elevation will get you a little past 900 yards, and you can then hold for silly shots to 1000 yards. If you were shooting past 500 yards all the time with 5.56, a 20 MOA mount would be best.
I came to the conclusion that a 0 MOA base would give you better optical quality at your 100 yard zero, which you could then hold for shots out to 600 yards (which is most all I'll ever shoot).
Is it feasible to hold to 600 yards with the MIL XT reticle on a 5.56 (requires about a 5 MIL hold)?
The math and reasoning:
The internet tells me you need about 4.5 MOA elevation for a 100 yard 5.56 zero. So with a 20 MOA base, you'd actually have to dial down (from center of elevation adjustment) -15.5 MOA to zero at 100 yards = worse optical quality @ 100 yard zero.
With a 0 MOA mount, your 100 yard zero would only be deviated from center +4.5 MOA (+1.3 MIL) = better optical quality @ 100 yard zero.
A 5 mil hold (which I assume is feasible on the Mil XT reticle?) will get you past 600 yards. So, with a 0 MOA mount you will have better optical quality holding to 600 yards than a 20 MOA mount. You would have to dial the 20 MOA mount all the way out to 500 yards to get the same optical quality as the the 0 MOA mount @ 100 yards, and dialed to 500-~700 yards, would have better optical quality.
So for shots out to ~600 yards using a MIL XT reticle, a 0 MOA mount will give you the best optical quality (which will be most of my shooting). The remaining 11.7 MIL of available elevation will get you a little past 900 yards, and you can then hold for silly shots to 1000 yards. If you were shooting past 500 yards all the time with 5.56, a 20 MOA mount would be best.
