Other than 3 frames of arrowheads that are very old I would imagine, it would be my Krag made in 1900. 122 years old and sill going strong. Pretty amazing I think.
That's an extremely cool Krag. You should explore the wonderful world of cast bullets in that rifle. The long neck of the 30-40 Krag cartridge is perfect for cast bullets.
These look like a good bet. I'd load them with H4895 to a velocity of about 1850 fps,...magnum primers to insure that the relatively light load gets ignited properly.
https://www.xtremebullets.com/30-Cal-165gr-RNFP-Cowboy-p/x30-165rnfpc-b0500.htmYou need to come up with a die that would put a slight flare on the mouth of the case to keep from shaving lead when you seat the bullet. Other than that, it's a fairly straight forward process.