I suspect we've made the same number of barrels..zero. But I'm also a tool and die guy. I can see where chasing a target dimension that changes with stress relief and different lots of steel can be different, as has been told to me by multiple barrel makers, could very well make it seem like, as you describe, "a big mystery."
Sure, there are parameters of acceptability, but there are differences even between steel lots and heat treats. Frankly, I'm surprised you didn't know this. When dealing in tenths, everything matters. But no, it's not magic. It's planning based on testing. From what I'm told, each lot is tested.
Of course I know that different lots of material, even though they fall within the specifications of ASTM guide lines, can have varing presentages of alloy content that can result in minor fluctuations in hardinability, ductility, and stress..
I do not think there is a “mystery” in the manufacturing of barrels. As in any machine work, you start with certain parameters that are essential in determining the the quality of the final product. Much of it has to do with the machinery and tooling at your disposal and how well it is maintained coupled with the skill and knowledge of the workforce.
You can’t make top quality products with sub standard equipment and unskilled personnel.
The level of quality does starts with the material. Since the majority of custom barrel manufacturers are using 416R for their match quality barrels, do you really think that any of them have a special deal with the material manufacturer so that their 416R is “special”? They may proclaim it in their advertising, but anybody that is the machine shop business knows that more times than not you are at the mercy of what shows up on the truck. “It is within ASTM specifications” is the caveat.
Of course, this does not hold true if you are dealing with a steel manufactured to your on specifications, such as the new material that Bartlien is marketing,
A number of years ag a rather well known person started making barrels. He put in his brochure that he was getting a special type of Stainless from Crucible. Everybody seemed to take is word for it.
Out of curiosity, I contacted one of my major steel suppliers and ask them if they could do a product search, specifically, I wanted to know Crucible‘s production runs and deliveries for the past quarter. It turns out that the 416R that had been delivered to this person was no different than any other run of 416R delivered to other manufacturers.
I mentioned this, to the chagrin of quite a few people. I got a call from the person wanting to know how I came by that information. How dare I even raise such a question..
So, rather than getting into a pissing match, I ordered one of his barrels and took a drop over to South West Labs to have a complete work up on the material. I also sent a drop off of another barrel from a different barrel maker
It turned out that within ASTM specs, the two pieces were identicl. 416R at 28 RC.
it cost me several hundred dollars to prove a point. I never heard another word about it.
By the way, that barrel did shoot pretty darned good.
