Pat Armstrong:  Apparently, Farmer the Joe (5MadFarmers) is an author.  Unfortunately, some of your question(s) got lost in our banter.  Barrel length is properly measured by inserting a cleaning rod from the muzzle until it stops against the closed bolt.  Mark the rod with a marker or piece of tape at the muzzle.  Remove the rod and measure from the tip to your mark.  Original length barrels will be 22 inches (Carbine) or 30 inches (Rifle) with a front sight stud neatly brazed to the barrel.  (There is also a very rare 26 inch barrel for the Board of Ordnance and Fortifications rifle).  Many Krag barrels have been shorten to make hunting rifles.  Commercial and various banded front sights typically give these away.  Posted photos of your rifle will get you a lot of info. and suggestions.  Does your stock extend to near the muzzle with a front barrel-band with bayonet lug or is it carbine length ending in a tappered wood tip inches in front of the rear barrel band?  Do you have a wooden hand guard on the top of your barrel with an opening where the rear sight would mount on the barrel?  These questions have a relevance as to the proper rear sight for your Krag.  Charles McArthur