I wound not worry about fpe - it has little or nothing to do with killing potential.
: Although a ML will deliver less fps with round or conical than a ctg. gun, even though identical charges are used, rest assured that any load of 150gr. to 200gr. is OK for most African game. A small bore rifle seems to require high numbers, as in 4,000fpr, or 5,000fpe to be effective on the large beasts of chase, at least that's what modern preferred rounds that are popular, provide.
: The ctg. 12 bore had 2 loadings. a 'light' charge, of 150gr.(5.5 drams) and a heavy charge of 192gr.(7 drams). These were charges loaded with round ball, for use on the continent.
: With fpe, even a small amound of extra velocity shows a large increase in the numbers, yet ther is no actual difference on the game animal. This-too, should show the value of these numbers - as in Nil. On the other hand, we all like large numbers, and use them for our higher velocity rounds, like the .458 RR Alaskan. Numbers above 5,000 are special, but in actuality, mean little. How can a 500 pound animal be hit with 5,000 pounds of anything, and stay on it's feet or inside it's hide? That would be like a 200lb. man being hit by a 2,000 pound object - would he stay on his feet? doubtful - even a 50lb. to 100lb. object in the chest would probably topple him.