Hello SS! The Kragcan be finicky about ammo alright. Ive had a few, some would feed anything, some would only feed RN bullets. As a hunter I stick with RN anyway as they expand better than most spitzers at Krag velocities. The hangup seems to be at the joint between the receiver and the side cover plate, where it's supposed to turn the bullet toward the chamber. You should see what my hunting rifle does to "ballistic tips."
I think you could get in there with a dremel or a die grinder and just fair up that joint. The metal on the side cover is case hardened and will take some work. Be careful not to cut deep into the receiver, which is a lot softer.
Good luck!
JN