Rolling block Identification

[Rocket_James]

Picked up my first rolling block but I am having trouble identifying the date and caliber. I tried 45/70 but the cartridge is too long and also a bit loose. Pics are hrre: thanks!

https://photos.app.goo.gl/iPrfU6WrSHXVb6gr7

[Bill Allen]

Try a 43 spanish, but the best is always take a casting. But a 45 70 will bottom out on a spanish. But it's in your best interest to cast it and compare it to specs remembering that the chambers in these old guns can be a tad loose. Bill

[marlinman93]

The vast majority of military Rolling Blocks are chambered in cartridges based on the Remington .44-77 bottleneck case. Remington tried to sell each country on the .44-77 case, but most wanted a case of their own proprietary cartridge. So they came out .43 Spanish, .43 Mauser, .43 Egyptian, etc. which are all quite similar.
So as Bill mentioned you should do a chamber cast with Cerrosafe, and then measure up the casting to truly know what you have.