The 9.3x64 Brenneke
The big boy of 9.3s was designed by German firearms genius Wilhelm Brenneke in about 1910. The 9.3x64 is still as modern as tomorrow. It's a true unbelted magnum; its rimless case has a base diameter of .504 (.034 of an inch thicker than the 7x57 family) with a rim slightly rebated to .492 of an inch. There is very little body taper, and the shoulder is fairly sharp, especially considering when it was designed. Case length is 2.52 inches, about the same as several of our .30-06-length belted mags. Technically, it will thus fit into a standard-length action, but overall length with the heavy bullets pushes (and in some actions exceeds) the limit.
The 9.3x64 Brenneke is not "better" than the .375 H&H, although its fans can certainly argue the point. It has slightly less bullet diameter, but its heavy projectiles have better sectional density. It will at least approach and (depending on who is doing the loading) can exceed .375 H&H velocities with bullets of similar weight. Since velocity is about the same as the .375, energy figures are also similar. The 9.3 does not offer the breadth of bullet selection of the .375 bore, but excellent 9.3 hunting projectiles are available. So it is no stretch to describe the 9.3x64 Brenneke as "the equal of the .375 H&H." And this is hardly damning with faint praise. The 9.3x64 will shoot at least as flat, hit at least as hard and can be used on exactly the same range of game (which means almost everything in the world). It has the advantage of the unbelted case design of so many of our hot new magnums. That isn't really a dramatic advantage, but it is more efficient, potentially more accurate and results in more compact ammunition.
Does that mean I'm ready to give up my beloved .375s and go to a 9.3x64? No, it doesn't, and although Chub Eastman is justifiably enamored of his 9.3x64, I doubt he's unloading all his .375s either. But so many writers (including me) have said for so long that the .375s (.375 H&H and faster) are the only sensible candidates for worldwide all-around rifles that it is taken as an article of faith. And if you consider ammo availability as a criteria, it remains true. But in strictest terms, it is not true and never was. The other cartridge equally deserving of the title is the 9.3x64 Brenneke. The 9.3x74R and the 9.3x62 Mauser are very useful cartridges, but the 9.3x64 is truly an alternative to the great .375 Holland & Holland.