I found BC information on a 210 Grain .308 caliber (which closely matches the performance of a 30-40)

fps/ mach     Cd        i7        BC(G7)       i1        BC(G1)
1500/ 1.34    0.379   1.033    0.306        0.574   0.551
2000/ 1.79    0.319   1.019    0.310        0.513   0.617
2500/ 2.23    0.280   0.984    0.321        0.494   0.640
3000/ 2.68    0.251   0.965    0.328        0.473   0.668
                Average: 1.000    0.316        0.514   0.619   
               Variation: 0.067    0.021        0.101   0.117

This is for a Sierra Match King 210 Grain G1 and G7. Dont have anything on Lymann, sorry

Hope it helps, and your Krag can shoot much higher than 1500fps. As long as the bore, bolt and barrel isnt damaged or mistreated you can go upwards of 2800+/- fps