With Winchester primer and wad, a 13 grain for 1200 fps is the only one listed; that limits your flexibility on this load. Your powder charge should be within 0.1 or 0.2 grains of 13.0 (normal variation on a loader.
With a slower powder, like Longshot, you will have a wider range of acceptable powder charges, with several muzzle velocities to choose from. With Universal, to try and get any velocity much over 1200 fps would result in too high a pressure.
With a slower powder, like Longshot, you will have a wider range of acceptable powder charges, with several muzzle velocities to choose from. With Universal, to try and get any velocity much over 1200 fps would result in too high a pressure.