I seem to find myself in need if any of you may know where some are hiding. Thank You in advance.

I don't have a spare set, but if you tell us about how you intend to load, that would help.
Before I had dies, I just used a bullet sized to slip snugly into a fired case. That was all for single shots.
For doubles, you can use a 30'06 FLS die to gently crimp the mouth of the case to give more tension on the bullet.
All of this depends on whether your chambers allow only a .450" bullet or if you can go all the way up to .458" and if you are planning on using black powder or smokeless (which generally dictates what diameter bullet you will want as well)

If this helps? I have a 500-450 and was lucky enough to find 75 rounds of loaded Kynoch ammo when I bought the rifle. Had I not found the ammo I would have stayed away from the rifle. I have not saw anymore ammo for sale in that caliber since I bought it. As far as dies go you should be able to reload the 500-450 with 460 Weatherby dies. That's what I plan to do. I used .350 Remington Magnum dies to reload .350 Rigby Magnum shells with several years ago and it worked fine. The principal should be the same with the 500-450 and 460 Weatherby dies. My 500-450 is currently being re-stocked by Griffin & Howe so I have not had a chance to shoot it or reload for it yet.

quote:

Had I not found the ammo I would have stayed away from the rifle.

Cases are easy to make out of 500NE or 470 brass.
That's what I did for quite a while until I found some Bertram brass with the correct rim thickness.
The cases made from 500 and 470 simply headspaced off of the shoulder with no issues at all.

I had problems with early Bertram brass being too thick for my double. Needed reaming. Bought some new brass, and whilst thicker than Kynoch, was thin enough to chamber. It has worked well.

Maybe CH for dies, I think that is what my 500/450 3 1/4” dies are.

I received the rifle today, a Rigby double made in 1879. I did a chamber cast and it is in fact a 500/450 #1 express. So now to proceed with acquiring the rest of the components to be able to shoot this old gal. I have a 500NE Merkel I have loaded for for several years. I would prefer to use a smokeless powder, just for less mess to clean up.

Well, that brings back some memories - I once had a Rigby hammer double built in 1891 with their rising bite action in No.1 Express, truly a lovely rifle!

These days my only nice British rifle is a Field action Purdey single shot in No.1 Express from 1896. I don't shoot it much any more, but I can tell you that neck sizing with, of all things, a Lee 45 Colt factory crimp die works perfectly with the Bertram brass I have. The Lee crimp dies have a carbide insert meant to smooth away possible bulges from crimping as the case is withdrawn from the die, and the one in 45 Colt makes a splendid carbide neck sizer for most 45 caliber rifles. The Lee crimp die for 45 ACP is just a tad smaller in diameter.

BP is less of a mess than you might think, and makes for a highly satisfying shooting experience!

I'll send you a PM with my contact info if you would like.

When I bought my 500/450 NE double I couldn't find dies.Hornaday said they could make them if I sent them two fired cases from each barrel then a forum member here found me a set of RCBS dies at a local gun store so they're out there just keep looking and post on every hunting forum.

I have put together an absurd reloading equipment set for this, since I have not found the correct marked dies. I have modified a 45/70 die set to work for now. I am using cast 340gr .458 bullets sized to .457 and lubed with alox. I have only tried
Accurate 5744 powder so far. 43grs gets me low on the target at 30-40 yards, about 3" low.

Low is OK for now, how was the regulation between barrels?