The calculators and programs are useful for the average to advanced shooter. As you know there is valid and quantifiable science behind shooting. The ballistics can, for the most part, be calculated and verified in field prior to hunting, competition or for professional use.
Of course there are so many environmental variables that can effect the bullet path, but the calculator will allow the shooter to take most of the variables (wind, density altitude, pressure, temp, angle, etc) into account and predict the placement of that first important shot. Also, instead of shooting and validating at 100, 200, 300, etc, you can set your zero and then validate your long distance shot. The algorithm with populate the remaining distances.
Not to get into a ethical debate, but as technology in bullet making, powders and glass has advanced, people are challenged to push the Max effective range of their rifles.
Calculators and programs can help make for a more succesful hunt or competition.
Personally, I use the G7 / LRBC program form Gunwerks gseven - Home
. This program has a vast library of bullets and ballistic coefficient info. You can validate your info at the range, then update the data for actual drop data for your rifle and elevation. Also if you have a Nightforce or Vortex scope you can print out reticle drop cards.
So in a nutshell, if you son reloads and likes to crunch numbers / collect data, then a calc is a good buy. Now that particular calculator is not as intuitive as most iphone apps, but it will be a nice addition to the range bag.