Leg colouring is entirely different genes.
Barring as in plymouth rocks (et. al.) has the slow feathering gene, giving time for precise detail to be created in the white bars. cuckoo- barring as in dominiques or marans has the fast feathering (as in "not-slow") gene, because the feathers grow more rapidly, there is less time for precise creation of the bars, and they are smudged.
Autosomal barring is a combination of genes; this gives a "concentric ring around the body" appearance. The barring gene does not cause the bars from one feather t line up with another. However, in a good quality barred bird, the bars will be precise and even, and if the feathers line up, the bars will to some extent, also.