I wouldn't use 3031 in a reduced load, only because an explosion of a .243 occurred with such a load. This from the American Rifleman, some 20 years ago. I have no memory of how light was the load; there was no firm conclusion about the "why?" of it.
I always loaded 20.0 grains of 2400 behind a 169-grain lead gas-check for reduced loads in my '06. I don't think you'd get too-high pressures by changing to the jacketed bullet, since the book's comment about muzzle velocity was around 1,900 fps. Start at 17.0 grains? Yo no se...