What is the alloy used in US Krag rifle bolt bodies? I believe the AISI 1325 used in its receiver is not what is used for its bolt body.

Is the bolt body heat treated uniformly? If it is, briefly describe it. If it is not, what occurred to obtain the Krag's remarkably smooth operation?

Is its [front] locking lug uniformly hardened through the entire lug? If it is not, what is the surface depth of lug's hardening and what is its HRC hardness range?

It is made from .55 to .65 carbon and .45 to .55 manganese steel (WD1350) and gets its smooth action from deep case hardening. And with that much carbon it is easy to get a through hardened part; when they went to the 03 Springfield after number 800K they reduced the carbon and increased the MN. And also it's tendency to crack the lug off. Remember that heat treatment in the 1890s and early 1900s was not as scientific as later, and some parts got too brittle; like 03 Springfields. And Krag bolts. Depth of case? deep. Hardness? Hatcher doesn't list it.

You may want to lap in the center rib per de Haas ("Bolt Action Rifles")to duplicate the Norwegian Krag. This will give you double the recoil area. Have the front lug checked for cracks.