Good point Fred.  I got one of those little One Book/One Caliber manuals for the 30-40.  It has Lyman data that goes up to 45gr of IMR4350 with the 220.  However, in the introduction, it states that the loads are for use in the Ruger single shot only!

There is also two sets of Hodgdon data.  For the Krag with a 220gr and H4350 it goes up to 42gr.  Then there's a section titled 30-40 Heavy Loads for Modern Rifles which tops out at 45gr for the same bullet/powder.