Shawn,
As Raimey stated your drilling is chambered for 12 ga 2 5/8"( not 2 3/4") and 8x58R S&S( aka 8x58 1/2R S&S). This cartridge is drastically different than the Danish Krag. It is one of the more popular of the Sauer and Sohn series of cartridges and is in the 30-30/32 Win. Spec. class of cartridges. It is a rimmed, tapered cartridge with a base diameter of about .433" and case length of a little more than 2 1/4". The current "school solution" for making cases is to shorten 9.3x72R cases, form in 8x58R sizing die, fireform, then final trim to length. Bullets are normally shown as .318" if jacketed, and a couple thousandths over this if cast. Early after the war, when metric cases were difficult to find, cases were often made from original length 38-55( 2.125-130") cases with the bullets seated "out". If I had the drilling, I would still use the long 38-55 cases( currently, 38-55 ammo is loaded in 30-30 length[2.080"] cases). Starline has the longer cases at a good price. The ammo you have is in a case a little over a quarter inch short, but seems to work. I would account for the reduced capacity with reduced loads, however. Buffalo Arms, and others, has .318" jacketed bullets in a couple different weights. Good luck and enjoy.
Mike
