I would just use the suggested load from the IMR catalog or what ever reloading manual you happen to have.

As far as I remember, the 30/40 Krag rifle was made in several styes, 1892, 1896 and 1898. Both in a rifle and a carbine.

People bought that gun from military surplus for next to nothing and did all sorts of things with it. Like change the stock and the sights.

If you had a origional Krag Jorgenson Rifle, in origional condition, it would be worth a lot of money right now to the right person.

I would try 45.6 gr of IMR 4350 and work my way up from there in 1/2 gr incriments to 46 gr which is a compressed load. Using a 180 gr bullet and CCI primers,