The problem with the smooth twist barrel and bullets is that bullets are spin stabilized. The effective spin on the pellet is not really sufficient to stabilize a bullet. If the smooth twist rifling has the same effect on a bullet as it does with a pellet it will not impart enough spin. I suspect, that, that will be the case.
Pellets tend to skid before they start to spin in the smooth twist which makes the spin rate slower than what the rifling twist rate actually is. Bullets would have even a greater resistance to spinning due to the additional mass (mass moment of inertia). However, given enough bearing surface the bullet may grab more than a pellet. This would be a delicate balance, I think, to have a bullet with enough bearing surface without too much additional friction going down the bore.