You make an excellent point about the handgun energies that can obviously kill cleanly. I will look up some of those energies and see how they compare.
It is interesting that you ask about range-finding. Dave King and I have been working on a "revolutionary" new system of GPS ranging combined with a ballistics computer for a completely integrated ranging system. I have to write the instructions today and then we will be making it available exclusively to the members of this message board to test.
My .243 is not exactly a "straight .243". I have a fast twist, match barrel that allows me to launch moly coated, Berger 95gr VLD's at just under 3300fps. At my altitude this bullet will stay supersonic to approximately 1850 - 1900yds depending on other factors.
I have made a hit at 1890yds already and that was with the scope not being properly setup. I had to aim "by guess and by god" to get onto the target. I have since had the scope mount fixed and should be able to go all the way to 2000yds once I find a place to set up a target and find a windless day.
I am using the lids from 55gal oil drums (24" metal circles) as targets. To see a short story and pictures of my first attempt go to:
and click on the "Shooting at a Mile" link.
The .243 is a good tool to practice ultra-long-range shooting but it will never carry enough downrange energy to kill anything bigger than a coyote. I did a rough estimation that at 1900yds, the 95gr VLD has approximately the energy of a .380 handgun which is not exactly a lot.