if your lathe is good enough to chamber a barrel then it is beyond what you need to make your own gauges for a .22 lr, if you just want to measure things to see where your rifle is at a fired case compared to that unfired case is about all you need given that you should have 1 thou or lass rim clearance on a closed bolt, 3 thou on a field rifle and no clearance on a bold action precision rig. the gauges are great for building a general purpose plinking rifle, in the world of precision I turn my barrel in until I am tight on an unfired case, of course i am using a coned breach face and don't have a milled pocket for the extractor either, but the same rules apply when chambering a new rifle, then the extractor slot is indexed and milled