I don't know if this is what's in play here, but in the history of long range shooting, there is a phenomenon known as "compensation" where a barrel whipped differently for different loads, and released bullets at different initial trajectories. The Enfield with it's flexy rear locking action was one such rifle, and companies such as Fulton of Bisley (not Fulton Armory in the US) would "regulate" Enfields to allow rounds to converge at the desired range (generally 800-1000 yards). The standard barrel M14 was another rifle documented to "compensate" (though to a lesser degree than the Enfield).
