As many have already said there is zero problem with the 458 Win Mag today! With modern powders the cartridge is a little work horse! I think I was probably involved in the discussion on another web-site you mention. I post there as MacD37.

There is no denying that the 458 LOTT is a superior cartridge to the old Win Mag, but it is not needed if the 458 Win Mag floats your canoe! Still as you say all the problems could have been avoided if they had just used the longer case in the first place, even with the powder they had in the 1950s. It could also been avoided by using a lighter bullet, made the case slightly longer, and seated the 450, 480 gr bullet seated out a little farther and still used the standard actions. Winchester's mod 70 was a full length 375 H&H action anyway, so that case could have been used, with no problem. The reason the 500 gr bullet was used was because though they knew the speed wouldn't be there in the 22" barrels of their rifles, the extra 20 grs of weight would give it more momentum, and equal the old 450NE 3 1/4" it was replacing in a bolt rifle. Rather than fix the problems when they became aware of them Winchester simply waited another 45 to 50 years to let the powder companies do the fix.

On the side of Winchester, they didn't experience the failures that happened in the field. That is because they were using 30" test barrels and shooting fresh ammo at their plant. It was a far different story in the heat of Africa, when the ammo had been bouncing around in the hunting car for days. The out and duds, and hang-fires were a real problem in a place where you don't need problems. By the time Winchester figured out the problem two or three private experimenters had solved the problem by simply going to a longer case. Watts was the first I'm aware of, followed soon after by LOTT. What amazes me is the guys who shoot the 458 Win Mag get so angry when you say the cartridge was a real dud in it's infancy, and say the problems experienced back when the 458 Win Mag came out are simply old wife's tales.

In any even the rifle chambered for the 458 LOTT today is a real deal because with it you have two choices of ammo if you ammo gets lost in transit. the 458 Win Mag will shoot in the Lott chamber with no ill effects, if your Lott ammo can't be found, much like the long, and long rifle in the .22 rifle, or the 38 spcl, in a 357 Mag. If however, the rifle is the 458 Win Mag the lott ammo will not work, also like the 38 spcl pistol can't shoot the 357 Mag ammo.

So with a two rifle safari being a 375 H&H, and a 458LOTT the 375 H&H will do the whole safari if the 458LOTT breaks, or if the Lott ammo is lost you can get 458 Win Mag ammo in Africa fairly easily. So no matter what happens you are not left with useing a crap camp rifle to do your safari.