Some members have shot 50 or more species of African animals with one rifle, in most cases a .375 H&H. I am not one of them. I have loved firearms since 1972 and since then, seem to have collected more than I need. Concerning dangerous game (DG) rifles chambered in .375 H&H and more powerful cartridges, I have more than I have safaris that I will take. Of my rifles of different chamberings (cartridges), for any safari I must decide on what cartridges I need or perhaps want to use for dangerous game.
The table below is a simple comparison of attributes of DG cartridges based on common factory and hand loads. Notice that the lowly .375 H&H has 4300 ft. lbs. of energy! With proper shot placement this will kill large elephants has has done so since 1911! For a 10.5 lb. rifle (total weight of loaded rifle with scope and sling, if any) the recoil generated in slightly less than 40 lbs. at a rearward velocity of 15.65 FPS. While this is twice that of a lighter 30-06, it is very manageable by most adult men and many women.
Increasing total rifle weight by one pound or slightly more than 9% also reduces the recoil by 9%. For a .375 this may not seem like much but reducing recoil of a 458 Lott or 500 Nitro by 9% will be noticeable by most shooters! Also, for rifles with the same total weight, the 470 Nitro popular in modern double rifles has twice the recoil energy as does the 375.
Decreasing bullet weight or selecting a faster burning powder that requires less weight to produce the same velocity will reduce recoil.
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Looking at the 458 Winchester we find the old standard of 5000 ft. lbs. of energy at 2150 muzzle velocity. This was what the much older 450 Nitro produced which was very effective on elephants. All but two of the listed cartridges generate near or over 5000 ft. lbs. of energy. Even the 404 Jeffery has 4700 ft. lbs. of energy. No wonder it has such a great reputation as an effective DG killer. Let us not forget that even the somewhat lower power 375 H&H and 450/400 have taken more than their fair share of elephant and other dangerous game!
Power (like speed) is good, accuracy is final!
Some cartridges such as the 404 Jeffery created in 1906 and the 416 Rigby from 1911 have greater muzzle velocity and power than when created. They are now loaded with much better gunpowder than the temperature unstable Cordite of their era. As for their killing effectiveness, the bullets available today are much more effective than those of a century ago!
Don’t forget bore diameter in relation to killing effectiveness. That’s the secret to John Taylor’s rating of Knock Out Blow (or factor), bore diameter times projective weight times velocity, divided by 7000,
i.e. (.375 x 300 x 2250)/7000 = 40
The Knock Out Blow makes sense in the greater the bullet diameter, the faster transfer of energy to the target. This also explains why all other things being equal and with the same muzzle energy, a smaller .416 Rigby even with 20% less bullet weight, will penetrate further than the larger .458 Winchester.
Please use this simple table to compare muzzle energy and its inverse, recoil energy and velocity. Hopefully all will find their happy balance of a powerful, personally accurate rifle at a good carry weight for their dangerous game safari!
Note: Above information is intended for those who are trying to wrap their brains around all of this. I hope it helps!
In fact she chose that 404 Jeffrey as her Plains Game rifle over the 275 Rigby HS we had with on our recent hunt. She doesn't like tracking to follow up game so appreciated the Hammer of Thor effect 
