I have been loading some .357 magnum Hornady 180gr XTP and seating bullet to the lower canalure. I just picked up another box at Midway and it only has one cannelure on top of bullet. I e-mailed Hornady & here is there response; On this bullet the lower or bottom crimp ring is actually a function of what press the bullets are made on some presses will need the lower crimp (knurled ring) to hold but bullet as the forward ring, or actual cannelure in rolled onto the bullet. With our increased production we now have machines that do not require a double ring and it is essentially a manufacturing item. Going forward you may or may not see the double cannelure depending on what machine the bullets are assigned to be produced on.