just bought one of these fine chamberings, but NOW What?
found one at auction, for what I HOPE, was the right price, and now realize this isn't the .577 NE A** kicker that I thought I was getting! Should have done a bit more research first, but all-in-all, will make a might interesting elk gun!
The big question; Where do I go about finding components, never mind just the brass for this round? This is a J&W Tolley sxs, with Jones underlever and hammers!
The only cartridge info to date has been through the "Cartridges of the World" by Frank C.Barnes. But, it shows two different conformations of the .577/.500. Should I do a chamber casting when it arrives?

Jimmy:
Congratulations on your purchase.
one version is about 2 3/4" case
the magnum is 3 1/8" case
chamber cast first, then….
dies, bullet sizer, shell holder from CH Tool
mould from NEI Handtools
Woodleigh makes thin jacketed bullets for the velocity
Brass at Huntingtons, may have to neck down .577 after a trim.
reloading data is easy, email or pm me and I have all you need.
.512 bullet sizers dies from RCBS to be used in their lube size machine.
buy Graeme Wright's for general double rifle info.
cheers,
Cal

Thanks so much for all the input, so quickly! The tag in the photos did list it as "magnum", but then they also listed it as an elephant gun!
Once I actually have the gun in-hand from the auction house, I will gladly send you a pm with more details looking for assistance. I am really looking forward to shooting this old girl. Thanks again for the response.

Jimmy:
PM at your convenience. I have the correct mould and can send some bullets to get you started but I will need to know the bore diameter from a cast so I can size them correctly. Your magnum is the much more desirable 3 1/8" case but is shy of elephant gun status but certainly large enough for everything except hippo, rhino, elephant, and perhaps a huge brown bear.
Contact when you can, but I will be in Kansas turkey hunting April 6-15.
Cal

Jimmy, great old caliber. Enjoy!