Here's my small bit: Where is the steel made? Not in PA I'm certain.
Second, Why don;t we go back to wrought iron www.realwroughtiron,com ?
Why not just use a suitable grade of steel?
While a good iron is better than brittle modern steel this does not make it the most logical choice.
Also iron, today is defined as steel with less than .05 carbon, so 1010 is steel, 1004 is iron. Then there is quality control.
Here is a factor. High quality steel is almost impossible to get in small quantities. Like a semi-load for example.
So while its possible to buy small quantities of almost any mill run steel getting the higher quality stuff is a lot more difficult. I can order individual bars of 4140 for example from MSC etc. but its MILL RUN steel and not only is the alloy not as closely controlled the quality control is just not there.
The high quality steels are sold in large lots, IE a furnace load at a time since the quality control starts before the material is even melted. Since the material is CERTIFIED to be what it is supposed to be.
Ruger, I have read, buys 100 tons at a time. The steel is MADE to their spec not only for alloy but for quality as well. And they check it in their lab before its even taken off the truck it arrives on. I have read.
Smaller makers such as Krieger have to pool orders to get steel.
So even smaller makers have to go to someone who has the steel and hope they can buy a supply or get in on and order being placed.
Someone mentioned the quench and anneal.
It is common to have the steel heat treated before its delivered. While its possible to heat treat barrels after then are machined and rifled and its important when button rifling is done its not really needed if the steel is right in the first place for the application. Stress relief is needed after buttoning to maintain the bore dimensions when the exterior is shaped.
While Krieger, for example, single point cuts their barrels the M1 Garand barrel has a rather complex contour and they claim they drill the barrels, then contour then ream and rifle to maintain uniformity of the bore. They do not mention any stress relief after contouring.
Machining a swamped barrel puts a lot of stress in the steel. It would be interesting to air gauge or otherwise closely examine the interior of a swamped barrel vs a straight barrel by the same maker.
What has all this to do with ML barrels. Rifle barrels are rifle barrels and the things that will stress a Garand barrel will stress a ML barrel as well. They are both "pressure vessels" one operates at less than 20000 psi the other over 40000 psi. But in efffect they both perform identical functions.
I know that 1137 will stand 50000 psi in a 45-70 chambering with not signs of strain, from lab tests, yet its widely considered unsuitable for even low pressure breech loader use by most and SFAIK has been abandoned for such use.
Even large firms with engineers and metallurgists screw up. I cite the 1140M Remington shotgun barrel fiasco. They could have used 4140 or 4150 but they went cheap. The material is subject to work hardening and some barrels shattered and people were disfigured.
So we have to ask why? Some corporate bean counter perhaps?
12L14 is designed for automatic screw machines. Its not designed for gun barrels. But like Remington some people know they can "get by" using it. Largely because they have the ever present "loading error" defense.
And then "everybody knows you can't blow up a ML barrel" this was "proven" when they tried to blow up that Springfield barrel way back in the 1950s or 60s or when ever it was.
But still there are failures. But since the failure rate for high quality 4140-4150 steels is extremely low even in military service with operating pressures often in the 60000+ range I find it unlikely that even a loading error using black powder, short started balls etc is going to produce the failures we see with low cost free machining steels.
So the only excuse is 1. Its easy for small quantity makers to get. 2. Its much easier to get a nice finish on. 3. They can be sold cheaper to people who put price over security.
Gotta run have a Marine to meet at the airport today.
Dan