The .458 Lott is a .458 caliber rifle cartridge designed for the purpose of hunting large, thick-skinned dangerous game animals in Africa. It is based on the full length .375 H&H Magnum case blown out and shortened to 2.800 inches (71.1 mm).

The .458 Lott was designed in response to perceived inadequacies and problems encountered with the .458 Winchester Magnum. The cartridge provides a distinct step up in performance over the .458 Winchester Magnum.[citation needed] A-Square, Česká Zbrojovka/Brno, Hornady, and Ruger have been instrumental in the cartridge's rise in popularity.

https://en.wikipedia.org/wiki/.458_Lott

I don't know anything about it but this has to be correct because it is on the INTERNET!!

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Ele era velho.
Ele era corajoso.
Ele era feio.

From what I recall Jack Lott was trying to duplicate the old British NE cartridge standard of 2200 FPS with a 500gr 458” bullet. The early 458 Winchester mag ammo had some issues with heavily compressed powder failing to ignite properly and most of the later factory ammo struggled to meet the initial reported velocity. Going off memory I think 2050 fps or so became the new listed velocity for .458 Win mag. Lott used a full length action and longer case to easily reach 2200 FPS at a lower pressure, which theoretically improved reliability in the hot environment of Africa.