The following is my view of the two cartridges formed by 6 years of field use of the Lott cartridge as my primary back-up gun on buffalo hunts in Arnhemland, Northern Australia.
I claim no practical field experience with Elephant.
Ballistics;
Despite what some would like to think, it is simply illogical to expect that a case which is 2.5” in length (Win Mag) can achieve similar ballistics to a case which is 2.8” long, given equal bullet weights and operating pressures.
In saying that, and in answer to the original question, there is absolutely nothing wrong with the .458 Win mag, just as it is.
Just ask Richard Harland !
The problematic load issues experienced with this cartridge (Win mag) have long since become redundant with modern powders.
Personally, I think, that with the current crop of modern projectiles available, specifically 5th and 6th generation projectiles as categorized by Pierre van der Walt in his book; African Dangerous Game Cartridges, .458 Win Mag users would be much better served by the use of the 450gn projectiles as opposed to the 500gn, which the Win mag struggles with a little.
Many vigilant handloaders will tell you it is quite possible to get 2150fps with the 500gn (Win mag), and this is true, but that will be from a 24” barrel only and running very close to maximum field reliable pressures in any climates.
Judicially loaded, and with a 22” barrel, the Lott will do 2250fps with the same bullet at much less pressure.
Many will argue if that 100fps translates into very much noticeable difference in the field and I would argue that that extra 100fps difference puts a .45 caliber, 500gn projectile into a very different performance category when specifically relating to buffalo, given that it has the structural integrity to sustain the impact velocity attained.
In seemingly contradiction to the above statement, there is very little, if any, visual difference between the Win mag loaded a quality 450gn projectile such as a C.E.B or North Fork loaded to 2250fps and a Lott loaded with a similar constructed projectile weighing 500gns at the same velocity !
My personal choice given the two options has always been the Lott, purely because I can get the velocity I know impacts hard on buffalo (2250fps), particularly in stressful situations, with reasonable pressures from a handy 22” (or shorter !) barrel, which to me is vital on a back-up gun.
Apologies for the long winded rant, above is my view only.
Regards,
Paul.