A Double Rifle in .458?
I am considering the purchase of a Heym double rifle in .458 caliber. The rifle has automatic ejectors. I have heard that because the cartridge doesn't have the flanged rim that traditional doubles possess that it will fail to eject reliably. Based on your experience, can you provide guidance on whether I should get serious about this purchase?
In this modern day and age, when good quality double rifles (like the Heym you mention and which I greatly admire) are widely available, I can honestly see no point in acquiring one which is chambered for a rimless cartridge, even if this cartridge is the popular and effective .458.
I assume that the double you are asking about is chambered for .458 Win. Mag. (or possibly .458 Lott), both of which are rimless cartridges and therefore better suited for bolt-action rifles.
In order to function perfectly in a double rifle, a rimless cartridge needs a specially adapted extractor and/or ejector that contains a small spring-loaded blade which pops up into the groove at the base that all rimless cartridge cases have. This occurs when the action is closed. If for some reason this system fails, the rifle will not extract and/or eject the cartridge case.
Rimmed cartridges are much better suited to double rifles because the extractors and/or ejectors have a much larger surface (the rim of the cartridge case) to grab hold of for case extraction. In other words, they do not rely on (for case extraction and ejection) tiny little springs and two blades that look like the tips of fingernails.
It was the well-known British maker Westley Richards who perfected the technique of getting rimless cartridges to eject from double rifles, and such doubles developed a good reputation. In fact, I once had a client who hunted a buffalo with me with a Wesley Richards double chambered for their .425 WR cartridge. This particular cartridge has a rebated rim (which is even harder to make eject) so I was intrigued to see how the rifle's ejection system worked.
It did, and well, but to be honest I was not impressed with how small and delicate those little blades actually were, and in the end I could not help thinking what a dumb cartridge choice that actually was for such an expensive double rifle. (Ballistically, the .425 WR is similar to the .404 Jeffery.) I looked upon the system with suspicion because it is my opinion that out here in Africa all mechanical things need to be really simple and very robust, and my sentiments have not changed over the years.
So, if you are serious about owning a double in .458 caliber, my recommendation would be to acquire one in the tried and tested rimmed .458 cartridge--the .450 Nitro Express. I have a game ranger friend who uses a fine English double chambered thus for all the big thick-skinned dangerous species (with 500-grain bullets at 2,150 fps as opposed to the more usual 480-grain bullets) and he is totally satisfied with its performance.
I have just returned from a hunt in the Zambezi Valley where one of our hunting party used, to good effect, a Heym double chambered for .450/400 NE. To be honest, I was highly impressed with its performance on a big bull elephant with 400-grain North Fork flat nosed solids (at 2,200 fps). If you are new to double or heavily recoiling large-caliber rifles, this would most certainly be an option to consider as this mild-mannered but highly effective cartridge is a lot more pleasant to shoot than any .458.
Another option to consider is a double chambered for .500/416. Performance-wise, this cartridge sits between the .450/.400 and the .450 NE, and I have yet to hear a derogatory word spoken about it. All these cartridges are rimmed and therefore perfectly suited for double rifles.
Knowing Heym and their rifles quite well, I'm sure such a rifle chambered for .458 Win Mag will work well--but I personally would not acquire it. Instead I'd go for one chambered for a well-proven rimmed cartridge.