If you plan to shoot mostly within 100 yds you may want to use a 50 yd zero.
I use a 25yd zero for all my ARs. Any defensive situations are likely to be at even shorter ranges than that, and even if not, it's within a few inches all the way out to 300 yards or so.
I sighted my wifes 12x scoped AR in 2" high at 100yds...