500BPE - in looking over your load, I believe I would maintain the use of all of the wads - the top and bottom pieces of the plastic along with the fiber and paper wads to keep the BP flame from melting the plastic and coating the bore with it.

What I now would experiment with, is cutting the folding fingers from the red wads to give more room for powder. I would experiment with 4 1/2 drams and 5 drams 2F or 1F.

More powder might/could/should have the result of spreading the barrels apart in their grouping to where they shoot perfectly parallel - thus, your leaf sights would be true at all ranges - what a glorious thing that would be - and fun at the range shooting gongs to the limit of the sights - THAT usually causes the spectators to question their scoped rifles & abilities.

Your 25 yard shooting shows the sights do you well, old eyes or not - you can shoot - that shows. So many shooters today cannot do with irons, what you have done at 25 yards.