Try out something White for a target.
White paper desert plates are not bad at 100 yards.
Use a Can, etc. to mark out smaller targets for closer range. Cut them out, and stick them on a contrasting background such as cardboard with spray adhesive, or just tape them on.
The Red Dot will show up much better on a White Target.
Makes centering the Dot easier to get a Zero on the sight.
See You At The Range