Federal™ Muzzleloader Bullets - BOR Lock MZ System - Manufacturer Review

http://muzzle-loaders.com/bullets/federal/federal-muzzleloader-bullet-trophy-copper-mz-FED239.php

The new Federal Muzzleloader Bullet features exclusive B.O.R. Lock MZ System provides outstanding accuracy in a non-sabot bullet design that's easy to load, scrubs fouling from the breech and ensures consistent bullet seating. The system's foundation is a polymer cup that is permanently attached to the bullet base. Before ignition, the polymer cup remains positioned at the rear of the bullet, with the forward obturating ramp exposed. At this point, only the fiber-reinforced base of the cup is in contact with the barrel. At ignition, the polymer cup slides forward and over both obturating ramps, creating the bullet's bearing surface and engaging the rifling. The resulting gas seal is incredibly efficient, optimizing accuracy, velocity, consistency and shooter confidence.
...