Gradous rifles.
Jon Beanland.
Greg Tannel
Short Action Customs
Clay Spencer
Gap..........
all these are very good, I'm sure others can add to the list, for pure accuracy and the best fit and finish I'd personally call Robert Gradous!
Any real smith should be able to do something as simple as screwing a tube on an action. The real measure of a smith should be how they handle a gun that they built that shoots like crap. I had a bad experience with two builders on that list. Turned into a cluster F both times...