i was going suggest you either try a bigger ball or a thicker patch. but not so much as you have to pack a hammer with you to load with.
my old smoke pole is in .54 calibre and the mould i have for it is .535 and i have to use a very thin patch to get good accuracy. the problem i have is the thin patches burns up. i have to use some kind of wadding between powder and patch to keep that from happening.(wasp nest works good for this) i been wanting to try a smaller size ball like a 525 or something.
i been feeling under the weather the last few days and coughing alot, so yesterday i went to see the saw bones. he tells me i got the bronchitis. he gave me a shot and some medicines and then on the way out he asked if i hunt, to which i replied yes. he said i got some bad news for you, that cough could linger for as long as a month. hunting season starts in two weeks here and i got a cough. dern this bad luck