Oh oh! I have to agree to respectfully disagree. !!!
Note happy face! The Brown Bess is not inaccurate. I'd say all smoothbores, or one smooth bore is as accurate as another. Regardless as to whether the barrel is in a NWT or a Musket. Both loaded properly, I don't think a Tulle or NWT will shoot any more accurately than a Brown Bess musket.
A smoothbore will hit a man out to 100 yards, but you can't place your shot precisely, in the heart-lung area of a game animal, for hunting at that range. You can hit the animal, such as a deer or bear, but it won't be placed well as with a rifle. Or, you may miss entirely. Again, effective against people, as if you hit your man in the arm or leg, he's out of the fight. Hit that deer in the butt or leg, he may run off and be lost.
You won't get all your shots into a paper plate at 100 yards. Herein lies the reason. When the ball does not spin, it will veer off course when velocity drops to a certain level. And round balls slow down fast. Usually around 70 yards. All things considered, around 60 yards, and especially at 50 yards and closer, a smooth bore will shoot with a rifle. At 70 to 75, a smooth bore shooting it's best, load development producing the best accuracy possible from a specific gun, will hit a paper plate every time at that range. But for hunting, I think that is maximum range.
The advantage of a "smooth rifle" is the sights. However, rifle sights won't keep the ball from going left, right, up or down after "around" 70 yards. The faster you can start a ball in a smooth bore, the longer it will retain it's velocity, generally speaking. Indeed, in a thick rifle barrel, (but smooth) one can load it very heavy, increase velocity and increase rang, but...enough difference to make a difference? It's rifling that makes the difference that is enough difference. !!!! Did that make sense. ?
My Bess is most accurate with 140 grains of 1fg Swiss. Accuracy drops off with lighter charges. For sure, to squeeze as much accuracy as possible out of a smooth bore, a lot of experimentation is involved, and what works in one gun might not shoot so good in another. My Brown Bess has rifle sights. (but "period correct")
So yeah, I'm absolutely open to friendly debate, but the Brown Bess is not an inaccurate smooth bore. Mine sure isn't. I've got three-inch groups at 50 yards. It is as accurate as any other. But all smoothbores have the same range limitation, because the ball does not spin.