No question about the obturation. If you remove the plastic skirt, a powerbelt bullet will drop down the barrel of most muzzleloaders. Yet when they are recovered from expansion medium or game, they have upset enough to have deeply engraved the rifling. The issue with this system is that there is a window of heat and pressure where this upset occurs as designed. At squib load levels, it doesn't happen. And at magnum loads, it happens to the degree that the stem at the base of the bullet deforms and doesn't release the plastic skirt. The latter scenario is not good for long range accuracy. BTW, I think the plastic skirt is only on there to prevent the bullet from falling back out the muzzle after being seated