What I find very strange is the whole statement and I either don't understand or its wrong. Ill explain, I had a gun built, and scoped and it was delivered to my address in Poland, I was in Scotland at the time. I loaded up ammo for it in increments of .5 of a grain, 4 grains above and below a similar gun I have in the UK. When I got chance I fired the ammo and found the most accurate and played about a bit as normal.
I went out on the rang and fired 5 shot groups from cold at 200 yards, adjusted zero and did it again. Then repeated same at 600yards. I sent the following information to the USA by email, Hight above sea level, direction of fire, wind speed, air temp, humidity, ranges fired at and how many click it took to get from 200 zero to 600 zero, bullet name weight and bc, in return I got a printout of my ballistic calc, bullet drops etc etc.
Next time out in no wind conditions I found bang on a 200, 300, 600, but wrong at 100, 1000. Re sent info and got new print out, this time spot on at every range.
When I went out in the mountains, checked on app what compensation I needed for my current Hight and air temp and first bullet sent an animal to write its last testament, shot was where aimed. So in my book modern ballistic calculations are spot on and I mean spot on. Sorry about the long winded explanation.