yes - both grooves and lands. I do believe there is obturation IF the charge is high enough in a round ball gun, otherwise, no. Can't prove it, but I believe it. Note how the .40 cal picket rifles need quite heavy for caliber charges in order to shoot well. This is probably due to the requirement for fairly high pressures to obturate the short, light bullets they shoot. Again, this is theory, not proven fact - about the obturation, that is. A round ball would, perhaps, need even higher pressure due to it's lower sectional density. Of course, velocity and rifling twists also come into the need for speed - so there are clouds in the sky.