I write on duct tape and put it on the opposite side of the stock facing away from me upside down.
For instance if you shoot right shoulder, mount your chart on the right side of the butt stock facing away from you when in position and put it upside down. When you want to read it when in position, just tip the rifle in towards you and you can read it the correct way. I find this faster than cocking my head in a weird angle to read the chart closer inside towards me if it were mounted in a conventional location.
I also carry a spare card with multiple elevations/density altitudes in a ziploc bag in my bino harness. This would only be used if doing an exceptionally long shot varmint hunting where the drop is really critical. For any big game hunting range inside 400 yards the altitude/density is not relevant.
Also a tip I learned from PRS, is generate your charts using constant drop values and not based on yards. This way you lookup the range on your card like normal, but the every drop value is an even number. It seems odd at first, but once you try it it makes sense and takes the guess work out of which elevation to use if you are in-between ranges.
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