1st let me declare that I do not endorse this method.
But I aim straight at the bullseye every time, as I'm sure you do.
It's just that the scope puts that aim on an elevation angle.
If he is zero'd (scope zero'd) at 1kyd, he can aim straight at any 1kyd bullseye.
Now if he does not mess with that zero, and reduces MV, his new zero can be any range to 1kyd.
If he knows what that new zero is, he can aim straight at his new zero bullseye.
Also, his reduced load was not stated as the same powder. It doesn't have to be.
Of course as air density conditions change, his new zeros would change.
But I suspect someone employing this method is not shooting at a level to notice.
As far as military sniping; most of it is walking shots into target and nothing impressive.
LE sniping does not have the luxury of walking in shots, but they're shooting point blank ranges.
Neither are good references for LR hunting.
If someone went to all the trouble to zero at 1000 then
develop different loads that could be used at 100, 200, 300, 400,500, 600,700,800,900
that would be on target each time by holding the main reticle exactly on target, I would not call them a genius....
Especially not in war, much less hunting. Only marginally mayyyyybe for benchrest.
In war, there is a saying called Kiss......keep it simple stupid.
What in hell ya gonna do w 10 different kinds of rounds in the middle of an assault? Oh hell I just shot the guber at 100 only he was out at 500..... You will be fouled up 3 ways to Sunday.
For hunting....Dang, that elk is headed over the hill at 400.
Now what color was that round???
Not to mention the ill effects on grouping accuracy of 10 different load combos where drop may work, but dispersion would sure not be your friend for sniping, hunting, nor benchrest competition.
Cant say I think this is really possible though maybe it can with super human effort be done by re zeroing experiments with each load......but it sure aint practical. Give me one load development for my rifle that groups well, and give me the holdover or hold under off ballistics and truing them.
Then I can go to war or hunting or even Benchrest.....with some logic that works fast, quick and easy. Kiss.
Tell that crazy guy, you dont want to be in his foxhole if hes watchin yore 6 with his method......just my 2 cents.