Norbert,
Staying with the .416 Rem/Rigby, we load the 330gr HV to 2700 fps, the 380 gr FN to 2500 fps and the 410 gr FN to 2400 fps. These speeds produce similar pressure levels and are well within CIP maximums.

The loads then calculate to the following values:
Bullet Momentum Energy at muzzle
330gr --127.3 --5343
380gr --135.7 --5275
410gr --130.3 --4861

Bullet Momentum Energy at 100m
330gr --121.6 --4875
380gr --120.8 --4179
410gr --116.8 --3910

Where is the difficulty or the impossibility? The 380gr FN is clearly superior to the 410gr FN and will also be less inclined to turn from it's path in the animal because it is shorter. The 330gr HV is devastating on Cape Buff and will shoot clear through any bull elephant skull from any angle.

A 400gr bullet is too light for the best result with a 458 Lott, especially if it is a Flat Nose and loaded too slow. A 450gr FN at the right speed will show an entirely different outcome. One should be careful about condemning something on the basis of one bad example.

This is why we recommend very specific bullets for the various calibers. Anyone can make a drawing, write the CNC code and turn a bullet but the final proof of the product lies in burning the powder and doing the comparative testing on game and not on creosote poles or wetpacks interspaced with saddle bags and such nonsense.

Nickudu, I think ,has the same insight and experience I am still battling: the 400gr Barnes ,doesnt matter which,cannot be loaded to 2400 fps or anywhere there,in .416 Rem Mag cases ,at least with RL 15 powder.
I can load the 370gr Northfolks ,being monos too.
Ray stated to me that he was able to load 400gr Barnes into Rem Mag cases,but I suspect he only loaded to 2200 fps or less.Dont know his loading data.

Jeff, for my money, go with the heavier bullets. So long as they shoot reasonably fast, deliver enough energy, you should get better penetration with the heavier bullet. Better penetration is what you're after with a solid, after all.

also, as far as problems with shooting both solids and softs to the same point of impact, I'd give it a try before worrying about it too much. With eland and buffalo the vital areas are fairly large, and I'd want the gun shot a bit to prove to me that the accuracy just isn't good enough.

I know all of this sounds too simple to be useful, but that's the way I'd at least try first.

I'll buy what Gerard says about the 380gr/.416cal GSC FN penetrating better than their 410gr/.416cal GSC.

But that 380 grain .416 is over 0.3 sectional density, and that is what I like to see for a penetrator/solid. It makes me happy and I ask for no more when 0.300 SD is reached.

Kind of apples and oranges, since the 350gr/.416 Triple Shock is a SOFT POINT, and less than 0.3 SD.

The guys answering the phones at Barnes are ballisticians ... good ones but how many buffalo they have actually taken is unknown to me. Their concern in recommending the 350 X is due to the case capacity of the Remington. Note, they do not tell you to opt for the 350 X for cape buffalo when using the Rigby or Weatherby versions. Why? Because they know you can drive the 400's fast enough with those casings. They assume the extra velocity of the 350 X in the Remington casing will out penetrate a possibly too slow 400 X if the latter can not be driven to 2,400 fps., disregarding the fact that the Rigby's reputation was built on a 400 grain bullet at nearer to 2,300 fps. than 2,400 fps. Put another way, they know damn well the 400 is the better buffalo bullet but are afraid it can't be pushed fast enough. I selected the 350 X (@ 2,500) for combination buffalo plainsgame hunts and was quite sucessful. However, I would go with the 400 X for "buffalo only". In one instance, with perfect shot presentation at 10 yards, the 350 X smashed the onside shoulder, took out heart and lungs and lodged in offside bone. In the process it shed all four petals and finished up at 242 grains. Did it do the job? Yes. Would the 400 have done better? IMO, yes, especially at close range. I have little doubt the 400 would have also smashed the offside shoulder, if not exited. For buffalo only, it is the better choice.

Jeff, If I misread your post, I'm sorry. Was it only in regard to the new solids they recommended the 350grainers for the .416 Remington? If so, I'd have much less of a problem with that, as the monolithics are so long, the numbers are still quite good at that weight.