The problem of slow loading of rifles caused by barrel fouling was solved by the Minié ball, which was invented in the 1840s by French inventor Claude-Étienne Minié. Despite its name, the Minié ball was not a round ball at all – it was long and conical, with an expanding skirt at the rear of the bullet. The skirt allowed the minié ball to be smaller than the barrel's bore, so it would slip in as easily as the ball of a smoothbore. When the weapon was fired, the skirt expanded to fit tightly against the inside of the rifle barrel, with less energy wasted in blow-by around the projectile and ensuring that the rifling lands and grooves would impart a stabilizing spin to the minié ball.