WB
While I'm currently working with the unique .450 No. 2 Nitro
Friday, January 22, 2021, 04:13

*To share what I found interesting and spreading some mostly useless knowledge. My partially edited cut and paste of the Wikipedia drivel.

My researching origins and data I found, naturally the ".475" side step. Eley created the .475 No 2 Nitro Express by necking up their earlier .450 No 2 Nitro Express. In fact it's not a ".475" at all! It's either a .483 or .489, the Brits glee in using the most narrow part of a bore to name a cartridge. We Yanks would better classify them as the .485 Jeffery and .490 Eley, but that would be too logical and Continental. One could easily distinguish and it not require any special knowledge. Easy to remember buying ammo for your $70,000 double.

History
The .475 No 2 Nitro Express is one of several rounds developed in response to the British Army 1907 ban of .450 caliber ammunition into India and the Sudan which saw the development of the ballistically very similar .500/465 Nitro Express, .470 Nitro Express, .475 Nitro Express, and .476 Nitro Express.

The .475 No 2 Nitro Express is a rimmed bottle necked cartridge designed for use in single-shot and double rifles. The .475 No 2 Nitro Express is a very large, impressive cartridge, the empty round is 3.5 in long with an overall length of 4.26 in.

The standard factory load fires a .483 in diameter 480 gr bullet at 2,200 ft/s, although two powder charges were available with either 80 gr or 85 gr of cordite.

.475 No 2 Jeffery
W.J. Jeffery & Co offered an alternate loading, known as the .475 No 2 Jeffery which fired a slightly larger .489 in diameter 500 gr projectile at 2,150 ft/s, although again multiple powder charges were available, with either 75 gr, 80 gr or 85 gr of cordite. Jefferys built a very fine handling double rifle for this round with a 24 in (610 mm) barrel that weighed only 11 lb (5.0 kg) but retaining moderate recoil.

WWI service - (The poor Kraut bastard first introduced to the Brit Elephant gun on the Battlefield)
In 1914 and early 1915, German snipers were engaging British Army positions with impunity from behind steel plates that were impervious to .303 British ball ammunition. In an attempt to counter this threat, the British War Office purchased sixty-two large bore sporting rifles from British rifle makers which were issued to Regiments, including a single .475 No 2 Nitro Express rifle. These large bore rifles proved very effective against the steel plates used by the Germans, in his book Sniping in France 1914-18, MAJ H. Hesketh-Prichard, DSO, MC stated they "pierced them like butter.

Use
The .475 No 2 Nitro Express is considered good general purpose round, suitable for all big game in Africa and India, its power is very similar to the .450 Nitro Express, with a larger diameter bullet; whether this is an advantage remains in dispute.

In his African Rifles and Cartridges, John "Pondoro" Taylor stated the .475 No 2 Nitro Express is "an eminently satisfactory shell and a certain killer - but don't let yourself be hypnotised by that great fat gleaming shell into the belief that you have something comparable with the atomic bomb to play with!"

Overall while the brass is expensive, some $5-6 each at minimum, I think it is worth it. For whatever caliber you wish to adapt it to. Truthfully the capacity is too much. But with so many modern powder options and surplus .50 BMG propellants some good use can be manipulated. It's also quite thick and robust. I think storage and age would end it's service more than firing and reloading them. It's a great piece of brass.