Looks like that is less than fun to do....
Are you turning your own bolt knobs or just threading bolts for them? I might have to look at my Howa 1500 and see if it needs a new one....
Fairly simple for a guy with a mill to do "one-offs" like this by mounting in a vice, lining it up properly and using a boring head to remove the outside of the knob. Fixtures to do "production level" are another story and have been on my "to make someday" list for a while now.
Allen, are you using fixtures or one-off setups? Doing it on the lathe?