Although I hear many in South Africa have converted their 458 Lott to the 3" .458 Express Belted Magnum (Several name for this exist), there is little to nothing available in this here in the USA. It is considered a Wildcat here.
Except. It appears I have one somehow. It does not say so on the barrel, yet it gulps down a 3.9" round without a qualm. Remember the Lott MAX COAL is 3.6". The 458 Express MAX Coal is 3.8". So I wonder on the history of my CZ 550, since I obtained it second hand with a bedded Kevlar stock.
The gun responds to loads like a 458 Express, and not like a Lott. The 3" Express offers significantly more volume, so can put out the same ballistics as the Lott with about 15% less pressure. Some think this fact reduces recoil, however you cannot fool Newton's Law. For every action, an equal and opposite reaction that is.
Less pressure is a good thing certainly. No shell binding, splitting, etc. If you want more power, then you can have it - because the pressure max remains 62,000 psi.
Personally, the Lott is powerful enough, and I plan only to take advantage of the reduced pressure on my upcoming hunt in May.