I would not load much shorter than 2.8" oal. Lots of folks have had problems with 150 grainers, mostly because they loaded too short to stack properly in the magazine. The Krag will feed most anything you put in it, as long as you maintain oal. For lead rounds heavier is better, keeps the velocity down and gives plenty of bearing surface.
Grafs, Midwayusa, Midsouth Shooters, Natchez reloading, Gander Mountain, Cabelas, Sportsmans Guide. Try them all, someone (Usualy Grafs) has Krag brass. Its seasonal, grab it when you see it.