The Lyman 50th Edition manual talks about how the MAP (max average pressure) of 40,000 CUP is what SAAMI has established for this cartridge.  It gives the history of the cartridge and discusses the Krag as an elderly military rifle, but it never gives any warning to not use these loads in the Krag.  It mentions you may encounter the 30-40 in the Winchester Model 1885, Model 95, and the Ruger Number 3.