Is that actually noted in a drill book somewhere, or is that from accumulated sniper lore?
I ask, because my PPCo (admittedly of completely unverifiable provenance) has the scope parallel to the bore in the horizontal axis (or is that the vertical axis?!); hence the POI remains offset to the left by a fixed amount at all ranges. Given that the offset is only about 1 1/2", it would seem pointless trying to have a "converged zero" at a specific range plus correction factors for every other range - far easier simply to aim 1 1/2" to the right, whatever the range.
Getting back to the OP's anecdote, the answers must surely be; (1) no, No1s do not typically exhibit lateral spread; (2) any lateral spread reported by the sniper is most likely down to a fault in scope/ mount/ shooter on that particular rifle....