Dphariss
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Posts: 8075
Should read needs to be significant to cause a problem. But this assumes a ductile barrel material.
Dan
I'm still pondering what this means. The shotgun thing at hunting camp was an example of supreme stupidity on my part and I really don't need help with that one. It was just my burst barrel story. I'm not looking for an arguement. I seem to remember using IMHO. I'm sure George was a swell guy who knew a lot of cool stuff. Wish I'd had known him.
OK I will stick my head in the Lion's mouth again.
Once the powder gasses reach a high enough velocity the bore obstruction causes a pressure spike at the base of the obstruction. I could point out some observations and reported problems from the brass suppository world concerning pressure waves traveling up and down chambers making multiple rings in barrels etc. But I think I posted it once before.
Cold rolled steels are not ductile. They are, by design brittle to aid in making them "free machining". They tend to break easily. Brittle is not suitable for shock loading such steels tend to shatter, so rather the bulging you may get fragments not unlike those seen from bursting bombs or arty rounds.. Shock loading is a factor gun barrels have to contend with. The reason I mentioned Remington was that they used, for a time, 1140M steel for shotgun barrels. The problem arises in that this steel, and others similar to it, WORK HARDEN. Shotgun barrels flex every shot. There were incidents where trap shooters (who shoot a lot) had barrels fail due to embrittlement from the flexing and there were some gruesome injuries, gruesome and blown barrels close to the breech are the norm btw. Now if the breech is heavier and the pressure lower there is little issue with work hardening. But shotgun barrels are very thin even at the breech compared to most rifle barrels.
Most of the steel used for ML barrels is brittle as it comes from the mill. Since its brittle it is weak when shocked. I.E a 100000 PSI brittle steel can fail for no reason at FAR lower pressures due their susceptibility to shock and internal pressure. Add to this the inclusions generally present in such steels and lack of care in making them compared to higher quality steels . Such as certified steels in gun barrel, aircraft or nuclear grades. For example I used attend matches where one of the competitors was a welder in the refineries in the Billings area. I asked him if they they used gun barrel quality steel in the piping etc. He said "no, its nuclear". Then he detailed the process for welding the pipes and other parts..... All steels are engineered for the job they do. Be it cheap hardware store grade screws, grade 8 bolts or gun barrels. I find it interesting that the US military has used essentially the same barrel steel, 4150 series, for small arms since before WW-II. They made the right choice and never need to fundamentally change the alloy.
If you read the comments by JC Kelly in the link posted above you will probably learn some things. Jim McLemore also has some valid comments.
What I am trying to get across here, and surely angering some people since I am speaking of brass suppository guns (its where all the data is). Brittle steels are not used for gun barrels in any application except American made MLs with "custom" barrels and a few surviving US factory guns from the 1970s that used "custom maker" barrels until people started getting hurt, Then they claimed they added an xray process to find flaws. But everyone knew, at least those paying attention, they had switched steels. You see certified steels are examined for flaws. Its part of the certification process. The Italian makers, for example, use a European grade barrel steel for their ML barrels.
Steels like 1018 have been used for low pressure smokeless applications and many, many firearms were made with them.
I would also point out that the ML makers and the ML barrel makers have the handloader defense to fall back on since there is no factory ammo for MLs. For example, this "faulty loading defense" 40 +- years ago saved a now major maker of brass suppository guns from a hefty settlement that could have shut them down. That and some creative chemistry that the plaintiff's attorney failed to properly investigate.....
Photobucket and some other sites came back on line so I will invite anyone interested to go to the link below. It would have saved me a lot of typing had it come up earlier..... Read "Barrel Steels - The Tough and Brittle" article if you are interested.
http://s72.photobucket.com/user/DPhariss/library/Barrel%20steel?sort=3&sc=1&multi=1&addtype=local&media=image&page=1Did I mention the time (circa 1993) I tried to get a "big" maker of custom ML barrels to cut a couple of barrels for me from 1137 GB quality which I had ready access to and he got nasty on the phone for even asking? I got the impression he lacked the knowledge to cut this steel and was not interested in learning.....
Dan
