My AR is a very customized Noveske. The COSUB on the Noveske was fired without shim, to determine a baseline for future zeroing.
1) 25 yards was a perfect zero
2) 50 yards was 3” high
3) 100 yards was close to about 8” high
Conclusion: The COSUB should be zeroed to a particular distance, a distance where most shooting is likely to occur. For my Noveske, I am shimming it to zero at 50 yards. That means it will shoot a couple of inches low at 25, right on at 50, and perhaps 3” high at 100 — not bad when all other systems fail. For a quick and reliable back up sight system (and even for a primary sight), at pretty much all practical distances, a 50 yard zero is the most prudent. Next, we’ll try our COSUB, zeroed at 50 yards, at 200 and 300 yards. We expect to hit a combat target out to 300 yards. We’ll report on this soon.