If it was important to drive 55- to 60-grain 243-inch-diameter bullets at 4000 feet per second, then the 240 Weatherby Magnum fills the bill. However, I think it's far more important to be able to comfortably drive a 100-grain bullet at 3200 fps. Comfortably; at less than sizzling pressure. There's not a lot to say about this cartridge, other than it's extremely accurate when the hand loader hits on the right combination. That combination (formula, if you prefer) should not include large rifle magnum primers, because the 240 is a magnum in name only. Case capacity is right in there with the 30-06 and other cartridges made from it. In other words, the 240 Weatherby is just about a 6mm-06. Add the nifty belt and that gorgeous double-radius shoulder, and presto!
My first 240 Weatherby was (I still have it) a Mark V ClassicMark with the 26-inch No. 2 barrel and tight fiddleback from butt pad to forend tip. My latest, and probably last one, is an Ed Brown Savanna Sniper with a Shilen No. 5 barrel; 26 inches plus muzzle brake, 8-inch twist for Sierra's 107-grain MKs. It was pricy. Weatherby now sends out the 240s with just a 24-inch barrel, and they've always had a 10-inch twist. Needs the extra two inches of barrel length. Also, my old Mark V has the big 9-lug action, which is capable of handling very large cartridges. It's totally unnecessary for the 240 at any stretch, but I like it.
It's a lot cheaper to shoot a 243 Winchester or 6mm Remington, and they only fall short by 150 to 200 feet per second when the comparison is fair and accurate. Other 6mm cartridges are coming along now, which will draw even more attention away from the 240. If Weatherby produced a Vanguard in 240 that had a number of features (26-inch, No. 3 or 4 barrel diameter, etc.) that lent itself to very-long-range shooting, I'd buy one in a New York minute, and I bet a lot of other people would too. I have a few retired Remington 40-X actions lying around, and building a nice 240 on one is an appealing thought. Eight twist for sure, at least 26 inches of barrel, no excessive free bore. It falls into the arena of "Why not?" After all, it has the most long-range potential of any commercial 6mm, and even more than some of the better-known wildcats such as the 6mm-284.
You probably noticed the muzzle brake comment above. Ed Brown and his son did some testing, and found there were accuracy advantages when using a properly designed muzzle brake on light- to medium-weight barrels. The No. 5 is a heavy sporter. No scientific arguments here. He offered it; I ordered it.