I've been doing something similar for years to help with my scope rangefinding. What I've been doing is to mark my side wheel or AO with symbols related to sharp focus at various ranges. I really don't care what the actual range happens to be, only the poi at sharp focus distances. For example..........
<a href="
https://imgur.com/7x895QB"><img src="
" title="source: imgur.com" /></a>
<a href="
https://imgur.com/FystEz2"><img src="
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After focusing, if the pointer lines up with a "
+" I hold "crosshair on the target". If the pointer lines up with a single dot "
." I hold one mil dot under the crosshair on the target. If the pointer lines up with two stacked dots separated by a slash "
.|." I hold target between the 1st and second lower mil dot. If the pointer lines up with two stacked dots "
.." I hold the second mil dot under the crosshair on the target.......so on and so forth.
The "downside" of my marking system is that it only works with one gun/mount/scope and one scope power setting. This isn't an issue for me because I only use one scope setting (15x for the Hawke on the HW95 and 16x for the Discovery scope on the R9).