IMPERIAL SPORTING .45 UP TO .499"

You are here

Home | IMPERIAL SPORTING RIFLE | IMPERIAL SPORTING .45 UP TO .499"

458 EXPRESS 3"

The 458 Express 3” dates from 1998 with the first rifles chambered in 2000. It was developed by South African hunter Prof. Koos Badenhorst, whom I knew well and had long conversations about the different 458 calibers Below is the text from the old website (458express.com).

458 EXPRESS 3" loaded with IMPALA bullet

PMP basic brass. The last specimen is for a local hunter who ordered a batch with a vanity headstamp.

  Pressure Test

  

Background
There will be very few in this world arguing the fact that the 458 Winchester Magnum inspired many caliber designers to develop and create new calibers. The .458 Winchester Magnum was developed in 1956 and the intention was to develop a large diameter cartridge that would fit in a medium sized action, (if .223 action size is considered as small, 30-06 action size is considered as medium and then 375 H&H size actions considered as magnum sized). I use this comparison simply because there is no rule cast in stone as to what size is in what category. Frank Barnes writes extensively about the 458 Winchester Magnum and many writers soon followed with countless praises and criticism about the 458 Winchester Magnum. In the late 1980's it was clear that the 458 Winchester Magnum did not do what was expected of it in Africa. Many ammunition suppliers claimed velocities of 2100 fps and even more, however in reality the 458 Winchester Magnum hardly ever produced these claimed velocities. The Weatherby "bigger and faster" giant size brass cases quickly intrigued many and we all know that the small 458 Winchester Magnum loaded with a .458 diameter 500 grain bullet made for a compressed load. Compressed loads are problematic in Africa due to the extreme heat and at the time South African propellants did not have the same stability as there German and American counterparts.

During the 1980's propellants were sold in batch numbers with printed reload data attached to every tin to ensure reloaders play it safe all the time. The 458 Lott followed on the 458 Winchester Magnum and the caliber soon took over from the 458 Winchester Magnum. Many rifle manufacturers started to chamber 458 Lott caliber and ammunition became readily available in America. Size counts as they say in the classics, but in the African bush many 458 Lott's also failed to perform. Complicating the matter was the fact that S321 propellant sold at the time in South Africa was not performing either. Very dangerous chamber pressures are generated in both the 458 Lott and as mentioned in the 458 Winchester Magnum. In combination with the high temperatures experienced in the African bushveld many a bolt action was getting stuck, like in really stuck. Can you imagine what this would do to your heart rate when a buffalo or elephant is charging. Even a very uninformed client will have no confidence in you instantly after such an incident.

I will never forget the day when I wanted to order a brand new 458 Lott and the gun dealer said "... no , no, they jam..."! At first I thought he was referring to the rifle brand name but soon realized he was very unhappy with the caliber. His experience showed that a client shot at a lion, and the bolt would not open for the second shot. Bullet placement was not good on the lion and the impact did knock it over, but the lion stood up, looking at a hunter with a total useless rifle in his hands. Few will be able to understand what emotions a hunter experience before he takes a shot at a lion staring at him, let alone how it feels after the same "now wounded" lion stares at you. Fortunately, they were not alone and the lion was then incapacitated by a friend. It had nothing to do with the brand of rifle or the 458 Lott per se, but the propellant and heat was the final factors causing a "jammed" bolt. Two extremely important lessons must be learned from this experience, first - bullet placement kills not calibers, second, do not reload and try the ammunition on dangerous or plains game unless you know exactly what the reloads perform like on the range, and the reloads are chronographed and pressure tested.

The 458 Express

With all the above Professor Koos Badenhorst set himself a goal to develop a cartridge that could be reloaded to well within the safety limits of a bolt action rifle and also a cartridge that would fit in a magnum bolt action. It was decided to use the BRNO ZKK 602 action as yard stick. Today we know BRNO is replaced by the CZ 550 product. There are hundreds of ZKK 602 actions and rifles in Southern Africa. The reason is that the ZKK 602's work well and are extremely reliable. Africa is called the testing ground of any product, the ZKK 602's passed with flying colors. The ZKK 602's needs no introduction in Africa, for many professional hunters it is our primary workhorse. The ZKK 602's are rough as dirt roads when you buy them, but soon with a little elbow grease and polishing media you have yourself a fine rifle with a smoother action.
The 458 Express was born in 2000. The brass case is 3.00". It surely utilizes all the space in the magazine box of the ZKK 602. When compared to other cartridges it is clear that the 458 Express towers over all the other calibers.
The very best attribute of the 458 Express is the fact that the South African propellants work in this caliber producing velocities of 2250 fps with a very safe working pressure! Another very important aspect is the fact that the lower chamber pressure, up to 13 000 PSI less, generates less recoil. Less recoil means more control and more control generates more confidence by the hunter. Only when a hunter is in control of his rifle and does not have a "flinch", he or she will be able to focus on bullet placement and enjoy the safari. The caliber was tested on numerous occasions in direct sunlight and in shadow conditions. No bolt-action failures were experienced, not once.

Straight Walled Cases
In many calibers the designation of "450" is used but the diameter of the bullets are indeed 458 inches. This erratic and confusing behaviour to name calibers by their designers can not be explained and we as firearm lovers will learn to live with it. As mentioned in other parts of this e-book the .458 Winchester Magnum has limited case capacity and constantly suffered from compressed loads. The brass case is 2.50". It is clear in the photo comparison that the shorter .458 Winchester Magnum is limited in space. The 458 Lott is only 0.30" longer than the 458 Winchester Magnum. It was thought that the limited space of the 458 Winchester Magnum was overcome, but the field trials soon proved otherwise. The 450 Watts was developed before the .458 Winchester Magnum and presented to the Winchester rifle company. I do not know what exactly happened but instead the shorter .458 Winchester Magnum saw production. A big mistake in my opinion! However, I do not have the decision in my hand to study and I am sure there will be a good one. The 450 Watts is 0.35" longer than the 458 Winchester Magnum and a mere 0.05" longer than the Lott. The 450 Watts is a .375 Holland & Holland length caliber. The .458 Winchester Magnum pushed the 450 Watts to the side and the 450 Watts never really had a chance.

Prof Koos Badenhorst studied all the calibers of the day and developed the 458 Express. The 458 Express is the caliber with the longest brass case and overall length of all the above. The caliber is belted, rimless and straight walled with a 458" bullet diameter. The large case capacity allows for less operating pressure and therefore less recoil. True 2150fps velocities can be obtained, safely, in the extreme conditions of the Africa with 500 grain bullets.