JKR,
Your groups are not bad at all. Most shooters and rifles/loads are 2 MOA or about 4.2" at 200 yards and you are close to that. Getting that down to 3" at 200 yards and 10 shots just requires working at it and/or getting better (more consistent) at casting and loading BP, refining your process. Every fraction of an inch under 3" becomes harder and harder and it takes time and effort, lots of trigger time. For me the process from start to finish is something I enjoy immensely. Whether is the casting or filling the cases or patching the bullets, I like it all. Having the desire to improve on my past efforts has kept me going for many years as a competitive shooter and I don't see my interest fading any. It's a great sport. Enjoy the journey.