I'm spreading second hand information.  One of the fellows on the 30-40 KRAG The Great American Rifle facebook page, who rebuilds Krags has used them and reported they worked well.  The man's name is Richard Ling.  He is using both Numrich and the Criterion barrels available from the CMP.  IRC he said the barrels from Numrich come with the front sight stud installed.  If you use the search function on the left the FB page, you can find Richard's post.  CMP sells both full length and carbine barrels.  However the sight stud is not installed like the Numrich barrels.  Numrich barrels come already blued, Criterions in the white.  To finish fitting either one, you'll need a chamber reamer too.  Those can be rented if the rental folks have one, or bought off ebay.