I'm surprised more people don't use a slower twist for round balls.I realize every barrel can be different.Tighter twists work well for conicals.I still use a montana rifle barrel from the MRBC on my .54 JBMR.35" long barrel.1 in 72" twist with my round balls.Thin silver blade front site.Used to target shoot it a lot at local shoots.
Sort of wish I would of kept the 30" barrel it came with as it had the serial number on the barrel yet,but I did'nt need it so I sold it.
I've had this gun since the early 1980's.Killed tons of deer with it.
Shot very well if I remember correctly at 50 yards.100 yards were a bit wider though but most in the black yet.I spit patch wiped in between shots with long underwear patches.If I did'nt it would throw a flyer now and then.Used .52 or tighter fitting .530 balls with lubed pillow ticking patch with usually 80 grains of FF.
I hav'nt needed to replace any parts on this gun,but showed through my research where the parts could be yet.