As great as that sounds... one could wind up in a great deal of trouble if they weren't extremely careful.  Ammo loaded for 30-40 used in a British Enfield - no problem, although the accuracy would suck.  However, ammo loaded for .303 used in a Krag could spell a very bad day for the shooter!  Higher pressures coupled with the .312 dia. bullet would be well over the acceptable 40,000 cup acceptable pressure of the Krag action. 

Food for thought, and one of the reasons I'm very hesitant to use .303 brass for my Krags.  Although I don't own a .303 Enfield, I may one day!