Bullet of the Week, Nosler Partition

Reloader · August 22, 2006

Well here it is finaly...

The Nosler Partition

[ QUOTE ]

“In the fall of 1946, a stubborn, mud caked Canadian moose failed to go down, despite a well placed shot from John Nosler’s 300 H&H. On the way home from that trip, John started thinking about a way to make a bullet that would perform well every time, no matter what the size of the game or the shot angle. Over the next year, he experimented with bullet design, finally settling on a unique, dual core bullet that was really the first Partition®. The following fall, John and his friend, Clarence Purdie, both killed moose with one shot using John’s new bullet.

[/ QUOTE ]

When I first set out to write this article I was under the impression that the Nosler Partition was the first bullet to utilize a two-part core separated by section of jacketing material. However, this was not the case. A German company developed the RWS H-Mantle bullet in which a two-piece core is separated by a portion of the folded jacket in between the two cores, another example was the Peters Belted soft point in which a separate band (belt) of gilding metal was positioned around and swaged into the shank of the bullet to stiffen it at midsection. These bullets appear to have been short-lived as I found little reference to them in other than histories of premium bullets. So despite not being the first, Nosler defintely takes the prize as the longest lived and most popular dual corred bullet.

The partition’s tapered front jacket and swaged lead core acts exactly as a soft point, expanding rapidly on impact, the inovation was in extending a thicker portion of jacket behind the base of this soft point bullet and encasing a second swaged lead core in the rear. This rear core was crimped into the cavity to prevent seperation even if the jacket deformed. The seperation of mass virtualy gauranteed a minimum of 50% weight retention, and subsequntly greater penetration on larger game. The bullet was originaly constructed by lathing the jackets and then swagging the cores into cavities shaping the final bullet. Though this first Nosler Partition was a vast improvement over soft point designs, the icing on the cake, so to speak, came through pioneering of Impact Extrusion techniques for forming the jacket prior to swaging in the cores. This produced the ledgendary uniformity and therefore acuracy of John Noslers bullets.

From todays perspective the Nosler Partition is a very simple design, and 50% weight retention wouldn’t raise to many eyebrows today, however it represented a dramatic improvement on then current soft point bullets in use on all but the largest and most dangerous game. As implied by the snip from Nosler’s website, the soft points of the day tended to shed jacket and core in fragmentation very rapidly, and failing to penetrate adequately, especialy under high impact velocities of the relatively new powders, and "magnum" cartriges being adopted during the first half of this century.

The Partition has undergone few changes in the last 60 years. The Partition Gold now encases the rear core in a steel cup to limit deformation of the base during firing in magnum rifles developing extreem breech pressures. However, the Partition legacy has spawned a host of newer premium bullets that incorporate some of its inovations and add a few of their own. One of the many examples is the Swift A frame, which utilizes a nearly Partition style construction but with a bonded front core for even greater weight retention.

Despite not being the first dual core bullet, Noslers creation not only provided us with a fantastic big game bullet, but also inspired a generation of premium development.

Adapted from various sources most notably Nosler's web site.

The previous partition designs were documented in an article on the history of Big game bullets from findarticles.com

OJR · August 22, 2006