This listing commemorates the excellent cast bullet experimental work carried out by Elmer Keith and Frank Marshall, Jr., which they shared with their respective readers in their gunzene articles — Keith’s in his various books main-line gun magazines, and Marshall’s in articles in the Cast Bullet Association’s [ http://www.castbulletassoc.org/ ] excellent members’-journal The Fouling Shot.
The two men were contemporaries and appear to have converged upon very similar optimal cast bullet designs independently. The two designs share features mainly in the portion of the bullet forward of the drive band section, and share the following valuable performance aspects. Both:
· Cut clean holes in paper targets;
· Deliver a powerful initial blow on game, followed up by a permanent wound channel considerably larger in diameter than the bullet’s diameter;
· Need no expansion to produce this exceptional performance on game;
· Penetrate much further than other bullets, progressing along a straight line and with considerable resistance to tumbling ~~~> it is common for a rear-end shot on large game species to traverse the animal’s entire length; and
· Exhibit no noticeable instability when transitioning from supersonic to subsonic flight, so are ideal both for very long-range plinking and for revolver/pistol loads with a muzzle velocity just over the speed of sound (the bullet will not destabilize when it passes down through the sound barrier, within a few tens of yards after leaving the muzzle).
Keith’s design is for use in sixguns and has a drive band section consisting three relatively wide bands of equal width. The rear two bands are separated by a wide, deep, square-shouldered lube groove, and the front two bands are separated by a deep crimping groove. The point, which is the secret of its game-getting ability, consists of a flat point (meplat) having a diameter around 70% of the caliber’s groove diameter, and is connected to the front of the drive band section by a broad curved (ogival) section that increases in diameter rearward until it abuts the flat face of the drive band section at around bore diameter. Therefore, the front drive band drops down a bit in diameter before meeting the point; thus, the Keith design is a type of “semi-wadcutter.” The bullet has a weight that is typical-for-the-caliber. Nevertheless, the bullet’s performance on game is all out of proportion to its weight, and achieves this performance over a broad range of impact velocities. It is mainly the ideal-diameter meplat that creates the bullet’s valuable performance characteristics on game.
By contrast, Marshall focused mainly upon the bullet’s point design, starting with a meplat of between approximately 63% and 73% of the caliber’s groove diameter, and, like Keith, favoring a radius (ogival) transition back to either the drive band section (for a revolver bullet) or to the cylindrical nose section (for a two-diameter rifle type bullet with a bore-riding nose) separating the point and band sections. Thus, Marshall’s two-diameter rifle type bullet is very much like the Keith design, but with a cylindrical nose section inserted between the point and drive-band portions. Marshall favored heavy-for-the-caliber bullet weights, but also included bullets of normal-for-the-caliber weight. Because all such bullets were accurate for either field or bench-rest use, gave sharp-edged holes in paper targets, and provided such exceptional stopping power on game, he referred to them as “Bench Or Woods Marshall” (BOWM) bullets. If a bullet had the right meplat, but missed other, less important, design features, Marshall referred to it as a “Semi-BOWM” design. Like the Keith design, Marshall’s design variants achieved their performance mainly because of the optimal-diameter meplat on the point.
Both Keith and Marshall avoided using an over-large-diameter meplat — too much of a good thing. If the meplat diameter is much above 73% of the bullet’s band diameter, the bullet will slow down too quickly, and will tend to lack stability at longer ranges; on the other hand, with a bullet having a meplat much below 63% of the band diameter, the beneficial performance characteristics listed above tend to diminish quickly. The “sweet spot” is a meplat diameter between 63% and 73% of the band diameter.
Because both of these great cast bullet experimenters converged on a narrow range of designs that derive their performance from an optimal-diameter flat point (meplat), NEI honors their convergent design by naming the NEI designs that exhibit the above-listed performance characteristics as “K-BOWM” bullets — “K” for Keith, and “BOWM” for “Bench Or Woods Marshall.” The list includes all of NEI’s Keith, BOWM and Semi-BOWM designs. Because bullets in this narrow design range are so ideal for target, for long range plinking, and for hunting large game and small game, NEI plans to add more K-BOWM designs in the future, and to update this list accordingly — new K-BOWM designs added after this listing’s first posting will be underlined. Be sure to have a K-BOWM mould in each of your favorite cast bullet calibers and to check back, from time to time, to identify new K-BOWM designs. You will really benefit from the way that these bullets perform.
If you shoot cast bullets at all, you will find it very helpful to join the Cast Bullet Association (CBA) at http://www.castbulletassoc.org/ . Membership costs only $20 per year. As a member, in addition to receiving the CBA’s excellent journal The Fouling Shot (TFS), every two months, you can purchase an on-disk ~200 page compendium of all of Frank Marshall’s superb Speaking Frankly TFS articles for just $10 (from the CBA website, tag the CBA Store link, and then the Other Publications link). Don’t miss out.
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