If your gun prints good groups I'd say just practice more. If your trigger is an issue, take it to a gunsmith and have them do a trigger job on it. I had my Mossberg worked over and it's not like a high quality rifle trigger by any means, but it's a whole heck of a lot smoother and lighter than it was originally. A ML may give you more of the feel of a CF than the shotgun does. If you have the $, go with a new muzzleloader. Any excuse for another gun is a good one.
rw