I was thinking....With only a .017" difference in case diameter (.441" vs .458"), and only .010" difference in bullet diameter (.446" vs .456), I would imagine it was fairly common for someone with a NMA in .46 rimfire to use .44 Henry ammunition in a pinch. The .44 Henry (especially the comical one) with its soft lead .441" bullet would obdurate into the rifling a bit under pressure, so it would be usable at short ranges).
Private 6 shot long cylinder conversions of the NMA into .44 Henry were VERY common, anyway, so they were not too concerned with the bore being oversized. .44 Remington factory rounds were only .448" in their factory centerfire conversions.