Here are a few photos highlighting the design features that make the Keith bullet work so well.
First photo shows the Keith design in both .44 and .45 calibers (the pair on the right). The .45 is actually designed by Dave Scovill, current editor of
Rifle and
Handloader magazines. Mr. Scovill noted there were no Keith style bullets available (with all of the correct design elements) in .45 caliber, so he persuaded RCBS to make a mold for one. The .44 caliber version is 250 grains, and the .45 caliber is 270 grains, even though the .45 version is notably shorter in length (it's the one on the left in that pair).
On the left are a pair of Veral Smith designs, proprietor of LBT - Lead Bullet Technologies. Both weigh 300 grains, again with the .45 caliber version on the left and the .44 on the right. Note how much shorter that .45 is, and how much less bullet it places in the case, below the crimp groove. Powder capacity, baby - that's why the old .45 Colt can actually outperform the .44 mag in a suitably strong revolver.
The next photo shows three .44 caliber bullets for comparison; the LBT, Keith, and a Speer 240 grain half jacket. Key design elements of the Keith that can be seen in this photo are the wide, flat nose followed by that secondary full diameter shoulder. These work together to actually
cut tissue out of the way, like a conductor's punch. A roundnose bullet, or a jacketed soft point, or a hollow point, merely
parts tissue before it, allowing that tissue to fold back into the wound channel, checking the bleeding to some degree. The cutting action of the Keith design "ventilates" critters far better.
Next are the three equal width driving bands. I explained how they work above. Notice the size of both the crimping and grease grooves when compared to the LBT. The grease groove holds several times the lubricant of the LBT design (which represents the norm for most of today's designs). The crimping groove is also beveled, allowing for a very deep crimp without working the brass so much, and also working to more gently and uniformly open the crimp upon firing. The crimping groove on the LBT allows for none of this.
The jacketed bullet is crimped over the front of the jacket, which is actually the best method I've ever seen on a jacketed bullet. We still can't get anywhere near the crimp we can get on the Keith design, but it is better than most. Most simply have a very shallow cannelure rolled into the jacket, which is wholly inadequate for heavy magnum loads with the correct slow burning powders.
These powders demand a great deal of initial resistance to bullet movement, so they can build adequate heat and pressure to burn efficiently. We use the heavy roll crimp in conjunction with larger diameter bullet to achieve this; I size mine to .431" dia, where jacketed bullets are .429" dia. The larger diameter provides a tighter fit in the case, for even more resistance to that initial movement. Jacketed bullets cannot be that large in diameter, as they would provide too much resistance once in the bore itself, dangerously raising pressures.
As a result, jacketed bullet loads are typically at their best using faster powders that do not require that heavy resistance provided by the heavy roll crimp and bullet pull in the case. Since they also provide much greater resistance once in the bore, the net result is very much compromised internal ballistics, resulting in much lower velocities than those that can be achieved with cast bullets. Couple that with their inability to cut a clean permanent wound channel, and we can see that the modern jacketed bullet is inferior in every way to the old Keith designed cast bullet.
So why do bullet companies peddle these things? Simple - they are easier and cheaper to manufacture in quantity than a properly designed cast bullet. Like so many things these days, economics trump everything else. Then it's the marketing boys' job to sell their latest whiz-bang creation to the unwitting shooting public. Hang a fancy name on it, show photos of neatly mushroomed bullets, and get the gun rags with whom you buy all that advertising space to tout the virtues of your product, and it's really the perfect crime. Gimme the tried and true cast bullet any day; it's by far the most effective handgun ammunition we can make. Just not very glamorous, I guess.