It's actually a hybrid. Unlike the power belt, when you ignite the powder charge, the "skirt" obturates around the lower part of the bullet becoming somewhat like a sabot. With a power belt, the skirt is stationary just forming a gas seal which allows the bullet itself to obturate to the rifling. That is why some states that allow connies only are having a problem with the Fed Bore Loks. And I think Colorado is actually having another look at them as well.