The Lyman is a dandy flinter. It probably has a 1:66 or 1:70 twist which would be an excellent roundball shooter.
Briman - As far as the flash hole bocking up - Do you use oil or any other petroleum based products in the bore or on the frizzen. This will combine with the burnt BP to create a tar like film. Real messy. Use a natrural lube after a good hot water cleaning in the bore and coat only the outside of the barrel with a quality gun oil. Keep any oil off your frizzen, fling and pan.
The old timers never had this type of fouling cause they didn't use oil. Their lubes were natural, usually mad of animal fat, most often bear fat.