Okay just spitballing here but curious none the less. Wondering if anybody ever built a 43 Spanish on a decent action with a properly chambered and rifled barrel. I mean built a rifle for accuracy. Now I know brass has always been an issue but Brother Dave has solved this here. 

I also understand the Sharps 44-77 is nearly the same and though I don't know anybody who competes or shoots one I've been told the cartridge has very good accuracy potential. So why wouldn't the 43 Spanish be about the same ? So I'll answer before anybody asks. Why would you want to do this ?  Well because it's odd and different of course. It could actually be somewhat easy if you rebbareled one of the Argentine Rolling Blocks that are floating around. They are reportedly well built actions and with some trigger work, maybe some wood and a good barrel they might answer.  Any thoughts

Rick

my 44/77 shiloh shoots lights out.  i also have an excellent argentine in 43 spanish i would sell for a good price  artr

The .44-77BN was originally called the .44-77 Remington-Sharps as both companies shared it's development equally. Remington sold huge numbers of rifles in this cartridge, and every time they were working on a military contract sale they tried to push the idea of chambering the contract rifles in .44-77 cartridge. But each time the countries ordering wanted their own proprietary cartridge instead of the .44-77 Rem-Sharps.
As a result all those cartridges like the .43 Spanish, .43 Mauser, .43 Egyptian, etc. were basically tweaked from the original .44-77BN they were based on. 
I've never had a rifle built up in the .43 Spanish for one major reason, the lack of a good source of plentiful, reasonably priced brass. Same reason I haven't chambered barrels in numerous other tough to find, and expensive brass. If it's easy to find, and cheap to buy I'm always happy to give it a try.