It is a known fact that a long barrel wipes over a longer distance than a shorter barrel. Our 28 inch barrels are definitely overkill for a powder like Blackhorn which is a progressive burning powder, but with other subs and especially black powder you start out much slower and with less whip. I really believe that with black and the slower subs like Pyrodex you need a longer barrel I like to have at least 32 inches on my traditionals but believe 24 is optimum for Blackhorn. I don't know where to place 777 as I never got past the crud ring far enough to do any testing.