I like shooting patch round ball. Here in PA we have flintlock only season for 3 weeks after Christmas, so I hunted that all my life. A tip that I can pass on about PRB shooting: is that some things work, and other things don't. There are general rules, but some barrels don't follow the rules. Anyway I find the right patch is a big player is getting a rifle to shoot well. I only use pre cut, pre lubed ox yoke patches. You can buy specific thickness and see what works the best in a methodical fashion. No guess work. Then write down that combo and stick with it.
I find moderate loads to be the best shooting. Too much powder seems to have inconsistent burning. I also seem to have better luck with 2F than 3F, but I only shoot 54 caliber.
Usually shooting sabots in an old school side lock builds up plastic in the rifling pretty quick. That buildup can really ruin accuracy. Maxiball seems to be a less frustrating pathway if you can't get a PRB load.
I also found a semi damp patch between loads help keep the bore consistent.
Anyway with a flintlock and black powder there are plenty of things you can screw up and provide much frustration. So keep notes and keep consistent.
https://rmcoxyoke.com/
