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Federal's B.O.R. Lock MZ System

A Veritable 200-yard Range Muzzle loader Bullet

Cutaway drawing shows sectioned BOR bullet.

by Timothy P. Banse

Some might reasonably argue that the technology for muzzle loading projectiles has changed little since the battle of Gettysburg. At least until now. Enter Federal's B.O.R Lock MZ system, an entirely new class of bullets.

Doubtlessly you are already familiar with the Civil War Minie ball, the cone-shaped hollow projectile of a narrower diameter than the rifle bore. How it worked its magic is as simple as the sea is salt. Combustion expanded the skirt so the lead engaged the rifling and sealed the bore, significantly improved accuracy and extending range in the process. Also important, the narrow diameter of the bullet made loading easier and quicker.

170 years pass, and little has changed. Muzzle loading enthusiasts still rely on the same basic principles, utilizing either a plastic sabot or an expanding base to seal the bore. Both methods boost accuracy and overall performance, but albeit with certain limitations. For example, one negative trait to projectiles fitted with a sabot is the force needed to ram a bullet down the bore. The sabot fits the bore tightly to begin with. Additional shots foul the bore making it progressively more difficult to ram a bullet in place. Another concern is legality. Regulations vary from jurisdiction to jurisdiction and some have outlawed a design where the sabot separates from the bullet proper.

facing images show unfired bullet and fired bullet mirrored by an expanded/mushroomed projectile

Another style of bullet features an expanding base replete with a soft plastic flange. This design can pose problems if the rifle is dropped or otherwise jarred. That's because a sharp jolt can rather unceremoniously separate the flange form the bullet, resulting in a gap between the powder charge and the base of the bullet. Even worse, the intrinsically soft flange is prone to rupturing during firing, which in turn degrades accuracy and bleeds off muzzle velocity. Because the bullets are typically cast of a soft lead alloy, terminal performance is not peak.

Enter Federal's studious ballisticians, garbed in white lab coats and hunkered down alongside their shooting chronometers and laptops. What they came up with has been dubbed the B.O.R. Lock MZ system, a veritable 200-yard range muzzle loader bullet. Unlike sabots, or belted bullets, the Federal design features a polymer cup permanently attached to the bullet base. Both the bullet and its cup measure a slightly narrower diameter than the bore. Upon ignition of the powder charge, the cup climbs forward and up onto raised banks strategically located on the bullet shank, effectively increasing bullet diameter, which in turn engages the rifling and seals the bore. The net payoff is of course optimized velocity and accuracy.

The acronym B.O.R. stands for Bullet Obturating Ramp. With B.O.R.'s polymer cup pushes up and out into the rifling the bore is sealed tight against combustion gas. Further, it features a hard, fiber-reinforced polymer ring the scrubs fouling all the way from the breech to the muzzle, decreasing the need to clean the bore between shots, and making it easier to seat the bullet each time at the same exact depth. Because there is no sabot, loading force is half that of most sabot bullets.

Suffice it to say B.O.R. Lok bullets are a quantum leap forward in muzzle loader technology. The bullet proper is based on Federal's proven Premium Trophy Copper rifle bullets and shotgun slugs. The projectile is all copper with a polymer tip inset into a deep, hollow cavity and skivving. (Skives are fracture lines cut into the mouth of a bullet jacket to improve bullet expansion.) Naturally it follows the BOR Lock high ballistic co-efficiency bullet lends a flat trajectory with minimal wind drift.

cutaway drawign shows bullet seated against its powder charge