I should have reworded that a little. You can shoot a Minie out of a smoothbore and out to about 25 yards or so you can hit a good sized target, but even at that short a range nine chances out of ten the bullet will tumble and keyhole the target. The originals had shallow rifling, 3 grooves, .015" deep at the breech tapering to .005" at the muzzle. A tight bullet properly made will upset into the deep grooves and as it travels up the bore will actually be squeezed. The lands were the same diameter the entire length. The twist rate for all original Springfields was one turn in six feet. Actually the standard bullet diameter was .575. This gives .005 windage in a clean barrel. Not great for target accuracy, but it did the job on the battlefield and allowed quite a few rounds to be loaded before wiping. But according to accounts from the period, at some battles with hot, dry conditions fouling built up fast and it wasn't long before soldiers had to pick up rocks and hammer their ramrods down or just pick up a cleaner musket from a fallen comrade. But for target shooting or hunting you can use a tighter fitting bullet and increase your accuracy. The standard load was 60 grs. of musket powder (slightly coarser than ffg. but not much different). You may find that 50 or 55 grs. works better, depending on the bullet skirt thickness or style of Minie. I've gotten good results with 40 grs. of fffg with some Minies. In the recent past I've done well with 50 grs. of fffg with a 480 gr. Old Style Minie. You'll have to experiment. Good luck with your shooting!
