Yes 1 n 20 is the twist you want. The original Sharps 45 cal. rifles had 1 n 20. To really get the best accuracy with this type of rifle you need to shoot black powder. It has been proven that black powder is more accurate at long range with this type of bullet and rifle than smokeless. Black powder shoots a very consistent velocity and the SDs are VERY LOW. You also do not want a Hard Cast bullet. Straight wheel weight is about as hard as you want and a bit softer usually shoots best. With black powder you also need a proper bullet lube. I make my own, 40% olive oil 10% STP oil treatment and 50% bees wax by volume. This lube is not necessarily to keep the bullet from leading the bore but it is meant to keep the fouling in the bore soft so the next bullet will push it out of the way and grip the rifling. Learning to load black powder cartridges properly involves a bit more than loading smokeless and you have to be careful handling black powder even down to not using anything plastic like funnels because of static electricity which will set it off. Then there is the proper cleaning up of the rifle and cartridge cases afterward. It is a real blast to shoot especially when you have good friends involved.