"Its just a semi wadcutter", how many times have you read or heard that?
The answer is no, not really.
The main difference between the 2 bullets is the center of gravity. Take a typical 158 grain SWC, and the 358429 bullet. Sit them upright, nose up, on a table top. With an imaginary line crossing through the center point horizontally, the center of gravity of the 158 grain bullet is below that line, in the Keith bullet it is above it, in the nose. So in horizontal trajectory the Keith is weight forward while the 158 is not. This is one of the most important keys to the superior accuracy of the Keith bullet, at any range but especially the 400-600 yard shots. Same as his 41, 44, and 45 caliber designs.