Original .58 Enfields were 1:72 twist. Most Italian repros are 1:48. My Enfield will hold minute of five gallon bucket at 300 yards and mushrooms nicely. That's with a charge of 70 grains of Pyrodex and a home cast Lyman traditional minie.
Back in the hay day of minie balls and conicals they used to shoot what was called a 40 Rod gun. They would target shoot at 40 rods/220yards, but would often shoot as far as 100 rods/550 yards. Their records are all sub-MOA, even at 550 yards. Yes these were benched rifles, but this shows you how accurate muzzleloaders can be.
Let's compare the ballistics of my .50 and. 58 caplocks, both shooting bullets out of 32" barrels with 150g charge of FFF.
Boomer
I must have misunderstood. Did you say the 50/58 barrel was (effectively) 1¼" (11/8) flat-to-flat?
If so, the 32" barrel alone weighs 63lbs?
Are these bench guns you're referring to?
CVA .50 and .58 barrels are only 15/16's in. thick flat to flot.
If you are even considering 150-200 yards, do not invest in a Enfield/Springfield-design musket. That type of [hunting] use was never their intent, notwithstanding whatever ladder sights they may have on [the Enfield].