Well, er, sort of...
Bullets spin well, but they loose velocity rather quickly, even real slippery Very Low Drag types. A 338 250 grain bullet is rather light for the task they were performing, kind of like using a 168 BTHP in a 308 and trying to get past 1000 yds.
In a nutshell, what happens is as the bullet slows, the center of pressure ( air pressure created by the bullet moving forward) begins to move forward and the change affects the bullets “yaw of repose” or kind of like angle of attack for an airplane wing. Then the bullet begins to wobble more and more until at a certain velocity for those atmospheric conditions ( air density-combined air pressure, temp and relative humidity). The wobble becomes more and more detrimental to continued forward motion and accuracy until the spin stabilizing effect is overcome and the bullet then tumbles and literally falls to the ground, if you will. Like a wing in a stall condition...
This happens with almost all bullet deigns at some point in free trajectory.
Some bullets tolerate the velocity decay better than others, and atmospheric conditions indeed are part of the equation.
Most bullets never make in free trajectory to those extreme ranges, they hit something first.
The 338 L would do better if a 300 or even heavier/longer/more ballistically efficient bullet were used.
This tendency occurs in what is called the transonic zone- a super sonic bullet slowing into the 1.3 to .8 Mach range (see, that is determined by atmospherics) has to stay stable through this “barrier” IOT to continue on to greater range accurately, while raveling at sub sonic velocity thereafter.
So, yes indeed, atmospherics and bullet deign can actually cause a super sonic bullet to “fall” out of the sky....
If they shot a 300 grain VLD, the ranges would probably be seen as a few hundred yards longer before they too encountered this phenomenon.
The standard twist for the AI 338 won't support anything much longer than a 250-gr Lapua Scenar bullet. And the 250-gr Scenar is preferable to the 300-gr Lockbase anyway because it shows better stability in the transonic transition than the Lockbase.
Corporal of Horse Craig Harrison was shooting an AI 338 and the 250-gr Lapua Scenar in 2009 in Afghanistan when he killed a Taliban from 2707 yards (laser ranged).
And the 168-gr SMK is known to have a design flaw that makes its stability questionable beyond 600-800 yards.