t4t Sir: i sssume you mean best in terms of efficiency. personally, despite long term efforts i have never been such a good shot that the differences you cite in randomly selected ball diameter, would, in and of themselves, have made a critical and measurable difference in my shooting.. for example, i can tell the difference between shooting my pet .54 rb gun offhand at 50 yards with 90 2f, .535 speer rb, and a .018 tick patch and shooting a hunting load formulated with different powder, ball, and patch. i suggest that its the totality of the shot and its purpose that that determines best. some of the best rb shooting i have ever done was done using visibly out of round shot on silhouettes. just shoot. be consistent in as many aspects of the shot as possible. sight picture is more important than .001 difference in ball size. good shooting. olduvai george