I was taught by a guy who has shot muzzleloaders for 60 years that with a new gun 20 rounds of lead bullets to start. Be it Buffalo bullets, Maxie Balls or patched round balls. Did this with every one I own and they are all shooters. When it ain't broke, is my thing.
One thing to be concerned about is plastic from sabots. My TC Encore started spraying bullets a few years back and this gun has always been a keyholer. Brushed it, solvent, plastic remover, the whole 9 yards and it was still pooched and had serious thought the barrel was toast. Went to my guy he said Sweets 7.62 bore cleaner was the only thing that will remove that plastic. Used it as per instructions and gun was back to normal next time out. The Sweets is only available in the US but it will cure a lot of ills in modern muzzleloaders. I have fixed 30-40 inline guns that went from good to bad and it is always a plastic buildup. 209 primers also compound this that is why I have converted to small rifle primers.