The one Krag barrel I pulled off was not extremely tight. Krag barrels are evidently more or less interchangeable, with tolerances being what they are some will be a lot tighter to make things line up.
Another forum member that had access to a milling machine built his own tools to replace a barrel also. If you go over this thread:    (You need to Login
Most people do not have access or know how on the milling machine. If you were to get the action removed with a pipe vice and shims to protect the barrel, the barrel going in to the new receiver could be tighter or looser. So you will have another opportunity to really score up the barrel. Also you will need to hold the new receiver so as not to break or ruin the finish while tightening.
If you happen to be near San Antonio you could bring it by here and I would attempt it. If successful I would like to keep the old receiver just to have one in hand when questions come up.