The following data appears in Cartridges of the World - 9th Edition, by Frank C. Barnes and edited by M.L. McPherson:
1. 75gr. HP bullet, 37.0grs. of IMR 3031 powder produces 3450 fps MV & 1980 fpe ME.
2. 75gr. HP bullet, 36.0grs. of IMR 4895 powder produces 3265 fps MV & 1770 fpe ME.
3. 85gr. HP bullet, 37.0grs. of IMR 4895 powder produces
3300 fps MV & 2060 fpe ME.
4. 90gr. SP bullet, 38.0grs. of IMR 4320 powder produces
3065 fps MV & 1880 fpe ME.
Dimensional specifications for the 6mm/.30-30 Improved
Neck Diameter - .275"
Shoulder Diameter - .392"
Base Diameter - .422"
Case Length - 2.03"
Cartridge Length - 2.55"
Hope this helps!
Steve Mace