I have been re-barreling center fire barrels for almost 40 years. There are some great barrel manufactures here in America. But there are some barrel makers who have higher standards than others. As it has been said often you get what you pay for.
I have seen my share of out of spec barrels over the years. Not just barrels not drilled straight or contoured with the chamber end and the muzzle end centered. I have seen barrels with cracks in them. I have seen over or under sized bore diameters, and tight and loose spots in the bore. I have had orders of ten barrels at a time come un rifled. The latest issue that I have encountered is incorrect land groove ratios. about ten years ago I bought barrels from a company. The first barrels I got were exceptional shooters. Then all of a sudden they went in the crapper not just for me but several gunsmiths had issues with this barrel makers barrels. I did some testing and the bore diameters were not as specified in the makers own writing. I later talked to a former employee of that barrel maker and he said the barrel maker did not even have the measuring tools to measure the bore diameters. That same barrel makers barrels after extensive examination were not properly lapped. They had tight and loose spots between the breech and muzzle. With another barrel maker I got barrels with hard and soft spots in them due to poor quality steel.
When you are spending your hard earned money on a custom barrel, you should do some research and check out what your buying. This may mean you spend a few exrta bucks having the barrel measured bore diameter, groove depth, land groove ratio, visually inspected and photographed for tool marks, proper lapping, other land/groove dsamage problems, and slugged for consistency. Get a written report including specs found, photographs, air gauge findings, and any problems noted.
CNC ball screws are susceptible to wip lash. Tight spots in barrel stock can cause ratcheting in both sine bar cut rifling machines. Pull buttons can hesitate when binding in tight or hard spots. Air bubbles in hydraulics also can cause ratcheting during the rifling process. Improper tool geometry and wear can alter land groove ratios.
Buying barrels does not have to be a "Crap shoot".
Nat Lambeth