Don't know where the link is but here goes:  Take  .303 brass and run through a .30-40 full-length resizing die.  Then load as you would if it were .30-40.  There are some very minor differences in case wall thickness, neck thickness, etc.,  but the only significant difference is that the neck on the .30-40 is a good bit longer than on the .303.  All this means is that your bullet will sit back a little further from the throat using the .303 brass than if using the Krag. 
Basically, the only thing that is reformed when you resize with the Krag die is that the shoulder angle is changed slightly.
I load mine pretty light and have had no problem using .303 brass and have had excellent reliability and accuracy.

daveboy