I know that there have been other postings regarding this issue, but I would like to post my personal experience with it as well.
I was brand new to black powder and purchased a Zouave from Cabelas a few years ago and was very eager to shoot it. Like a dummy I forgot to order any type of accessories and had no idea what to get so I started from scratch.
I have seen movies about the Civil war so I knew that I needed some kind of caps, balls and powder.
I found a local store that had pyrodex and caps, and no balls, so I told the person the caliber and all they had in stock was a .575 round ball mould. So I bought it.
To make a long story short about the caps, I never knew that there was more than one kind, so I had to drive back and exchange them for “musket caps”.
I spent a good weekend molding balls from lead weights that I had in the garage and the next morning, I was off to the range.
I put in a charge of 50 gr of pyrodex and then tried to force the ball down the muzzle with a small “home made” patch from a gun cleaning rag that I had. The darn thing was so tight that I only was able to force it ½ inch into the muzzle with A LOT of pounding. Something told me that this was way too tight because I remember from old movies where people used to “gently slide” the ball and patch down the barrel with a ramrod.
The range was pretty far from my house and I didn’t want to have to drive all the way home without firing a shot, so I took my knife and slowly “picked and scratched” out the stuck ball. I then took a new ball and just placed it in the muzzle and it gently rammed it over the powder until it was seated. I shot a few times like this and found the musket to be very accurate at 50 yards and also hitting regularly on 3 ft targets way past 100 yards.
After the ball started to get too hard to load, I swabbed out the barrel between every 10th shot or so to keep down the fouling. I ended up shooting all of the home made balls and most of my powder that day and had one of the most memorable experiences while shooting black powder.
Later on, I also bought a J.P. Murray carbine with 24” barrel (basically it is a shortened version of the Zouave) and tried firing some mini-balls, The first ten or so would “keyhole” on the paper target. so just for fun I loaded the mini ball backwards (sort of like a poor mans hollow point). And guess what? It shot more accurate then ever and never, leaving perfect round holes in the paper target.
I found out later that the bore size on both of these muskets was .577 which would explain the tightness of my loading experience.
I eventually bought a more correct version of a ball mold of .570 and started using patches with great success and stopped using mini-balls because I could just never seem to get them to shoot correctly.
Live and Learn I always say.