The number of machine shops that fail to produce parts to acceptable standards for any industry is a topic worth discussing.
Your referencing volume based manufacturing, profitability, and subcontracted barrels for large firearms companies. Those are all kind of related subjects but not at all addressing why you disagree with my argument that vocational skill trumps job title.
I’m talking about a competent person, who is vocationally trained having the ability to chamber, shoulder, thread and crown a prefit barrel from a reputable barrel blank.
Explain, what voodoo they lack to perform the task?
Specifically, why is the gunsmith capable of making that part “better”?
Machinists are trained to be efficient and use the quickest method to accomplish a task, and part of making a plan to machine a part includes an understanding of the material, the drawn plans, what’s not on the plans, the end user, what will be tested and what tooling is available. A set of blueprints is not going to list a tutorial on barrel manufacture practices, or discussion of the potential pitfalls of testing chamber dimensions.
Barrels are line bored after profiling the exterior and the bore is never exactly in the middle - that’s assumed common knowledge for gunsmiths.
Every year I see a professional journeyman machinists show his after hours project on a forum and the barrel is set up in a standard three jaw chuck for threading and chambering, oblivious that he’s setting himself up for trouble. That’s where egg shaped chambers are born. Of course others that know better point it out, and a half cooked excuse is made that he checked concentricity, or that it doesn’t matter because the reamer holder will float enough to make up for it - that works until it doesn’t.
I’ve seen QA setups for checking tapered holes with an internal shoulder and it might have one go/no go for outermost part of the taper, another for upper part next to the shoulder - that’s in addition to regular headspace, neck, and throat depth. Guess what happens when someone doesn’t clean all the chips off the reamer and leaves a ring in the chamber between the shoulder and base - the knowledgeable machinist without gun experience knows the taper QA check indexes at the top of the taper and another at the bottom, and the SAAMI spec allows .002” over nominal. He polishes out the ring, blends it in, and nobody knows until fired cases stick. A simpler single go/no go taper check will miss oversized ends. I doubt most barrels are even checked, let alone checked that closely.
I don’t claim to know much about CNC chambering and have not paid attention to those discussions, but there are many threads between those in the business and experienced machinists trying to get their technique and setup figured out.
Journeymen machinists are great at getting jobs done and being efficient - 20 years experience doesn’t prepare them to know what they don’t know, and what shortcuts work and which don’t in this specialized situation. Once they learn what is the common body of knowledge of gunsmith barrel threading/chambering they will be every bit as successful as someone who started out a gunsmith, but not all of it is intuitive.
A relative is a top pastry chef, and she chuckles when a sous-chef thinks something should be easy, jumps in to help and falls on his face. Lol
