I have a Persian mauser k98 circa 1935 in 8x57. The bolt had been changed when I bought it, plus I noticed a small setback on the recriver's lug recess. I took the barrel apart and lapped the lugs but it went more than what it should. Nearly 8 thou" .
The good thing is that it seems all that lapped material are gone from bolt lugs only and not from the recriver's. I say this because the headspace is increased the same amount as what it is removed from the back side of the bolt lugs.
Another good thing is that bolt lugs back surface still pass the file scratch test and are hard as what they were brfore lapping.
In short the whole process was like this:
the chamber was .012' longer than standard go guage, the first step.
Took the gun and barrel apart.
lapped the lugs by 0.008'
I had nearly 0.02" excess headspace now, both from the chamber being long and lapping process.
I cut about 0.01' from the chamber's end of the barrel on my lathe.
turned another 0.12 from the outer shank of the barrel but kept yhe chamner area intact (only to make the barrel enable to turn 1/6 turn more into the recriver) to compensate for breech to barrel distance that was increased
Cut 0.02' from recriver's face snd trued the C ring.
assembled the whole thing
Everything seems ok now, the chamber passed the go nogo guage test, the distance between bolt face protrusion and barrel face is 0.006 inch, and barrel is torqued and snug, But I am still worried about the hardness of bolt lugs.
do you have any idea on this , I know that the bolt and receiver are case hardened on mausers , but I got the idea that the lugs are probably hardened all through.
Thanks
Mike