Fred, we have thrown that one around for a while. I don't think anyone can state for certain what the "last" Krag was  that was built. Springfield Armory continued piecing these things together long after the official "Stop" date for production because they had lots of extra parts in the parts bins and fixed and updated Krags for years.

My highest Krag number is 482709 but I have seen a few higher.  Mallory's 1st edition lists the highest observed Krag serial number as 489840.

Without searching through my other references, I do believe there have still been some higher numbers seen since this listing in Mallory 1st edition.  Mook lists number 505999 as having been manufactured November 1903. I don't know his reference for this.

Maybe we should all chime in with high numbers known.