Re: "Thermometer" target
That's easy; make an aiming point and draw a vertical line up off the center and make reference marks where the point of impact above the aiming point should be at appropriate ranges.
Example with my .308: precise aim point at the bottom of tall paper target (I like to use the corner of a square with riflescopes for aim point), vertical line straight up, reference mark for where I expect the trajectory of my bullet to be at 100 yards with 600 yard zero= 16.32" above point of aim and a mark at 28.70" for 200 yards.
You need to use a ballistic calculator and punch in all your info to get the impacts above point of aim for your specific setup and environmental conditions.
Courage is just fear that has said it's prayers.
The people trying to say the 2nd Amendment is outdated are probably the same folks that would say the same thing about the Bible.