I am not an expert on all things Krag, but I removed an old barrel from a sporter and was surprised how much larger the chamber was compared to unfired ammo. Over .010 in this case. I had thought the soft steel barrel had stretched with many shots fired. Others on this forum said that was normal.

In the old days before good high speed steel was available for reamers they used carbon tool steels. The reamers were originally made very large then got smaller as they were resharpened during their life. So the resulting chambers could be large or small depending on when in the life of the reamer an individual barrel was made.

Now to your cases, is the bulge all in one spot or does bulge appear smooth all the way to the neck? Is it concentric all the way around the case? Is it just on the ejector side of the chamber? If it is just one side you will be able to feel it by spinning the case in your fingers.
If it is just on one side of the chamber I would be concerned till I figured out why. A severe overload could conceivably bulge just the extractor side. Water or another corrosive could have been allowed to sit on one side, and be later "polished" out.
Reloading will be in your future if you continue to shoot a Krag, if the chamber is just one of the larger ones, neck sizing the brass will keep from over working the brass near the rim. Minimal sizing could work with just a bulge on one side, this would allow the cases to chamber if the bulge was not lined up with the large side of the chamber.

Photos could help if the bulge is visible, or outline the bulge with a marker if it is not.