italiansxs,
Not to pick nits, but neither 458 Win nor 460 Weatherby are rimless.Rather they are belted.
Mike
Mike:
The 458 Winchester Mag is essentially a rimless case with the rim and belt diameter being one and the same at .532.
The 458 is based on the 375 Holland & Holland magnum. Here's the writeup on that cartridge:
"The .375 Holland & Holland Magnum is a medium-bore rifle cartridge. The .375 H&H was only the second cartridge ever to feature a belt, now common among magnum rounds.[1] The belt is for headspace, due to the narrow shoulder.[2] The belt replaced the rim in function on these new rimless cartridges."
Also keep in mind that back when the 458 Winchester Magnum was introduced African hunting laws required a rifle cartridge of .40 or larger for hunting dangerous game. So this I believe is the primary reason Winchester developed the 458 for a bolt action Model 70.
Jim