Hi Chris,
I don't know how useful this will be to you. You may not be able to get the cast lead bullets we can get here in the US.
My .38/55 is a restored Winchester Model 94 with a 26 inch barrel that has a 0.375 inch groove diameter. I use the shorter Winchester cases and Winchester Large Rifle Primers. I shoot all my groups at 50 yards. The rifle has a Marble tang sight.
1.) 19 grains of IMR-4198 with a 260 grain SAECO #373 cast lead, gas-checked 0.376 inches in diameter bullet. Overall length = 2.49 inches. Average muzzle velocity = 1367 fps, Average five shot groups measured 1 1/2 inches; the best was 13/16 inches.
2.) Same as above except 27 grains of IMR-3031. Muzzle velocity= 1402 fps; group size= 1 1/4 inches.
3.) Same as above except 23.3 grains of Reloader 7. Muzzle velocity= 1495; group size= 1 1/4 inches. 100 yard group was 2 3/4 inches. This is the best load in my rifle.
A source of SAECO #373 cast lead bullets is Mt. Baldy Bullet Co., P.O. Box 835, Cody, WY 82414. Weebsite:
www.mtbaldybullets.com
Good luck and don't forget to slug the bore first and don't try to "hotrod" the .38/55.