It's very possible that either the conditions or the examples I had skewed the results.
I have noticed that there is noticeable sample variation in ATACRs. Is it possible I have an exceptional 4-20 ATACR and the ZCO was a dud?
@CSTactical I am aware that the internet loves the 4-20, but that's not what I saw. Can you pull both out and look through them for me? I don't currently own both. Both myself and a friend had the same conclusion when comparing the two 4-20's. FOV and eyebox were the most noticeable differences with the ATACR winning in both of those categories.
Richard, I did adjust the diopter on both, so I don't think that should have been a factor.
Most of the reviews compare the ZCO to other ultra-shorts. I find all of the ultra-short scopes to be lacking. With the ATACR being a non-ultrashort maybe that's why it fares well?