It is true,many mausers have been stup for longer cartridges.I stand corrected.
A setup I have used successfully on boltfaces ,I have an angle plate with a vee-block on one face.I set it in the vise on a Bridgeport,and put the bolt in it.I center up with an indicator,then use a small boring head with a carbide boring bar,just a small stoned corner break for a radius.
I use magic marker to get my touch-off,with the mill in neutral.Then I just dial .001 or so,whatever works,on the boring head,and turn the spindle by hand,scraping out the diameter.Then,I can come back with a1/2 in end mill and just barely skin the bolt face,and then offset the .017 or so to clean the sides
All one setup.