No I did not say that I didn't read all the spec's and maybe even understand the tec reasons ,what I said is I do not have the ability to do the tests the G has .
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No I did not say that I didn't read all the spec's and maybe even understand the tec reasons ,what I said is I do not have the ability to do the tests the G has .
I'm not sure that the metallurgy tells us the whole story. In short the barrel must sustain X rounds before deflecting or sagging under sustained fire...
4150 allows for sustained fire from an M4 or M16 with deflection that does not endanger the soldier.
In short, the NOTICEABLE difference in 4140 vs. 4150 will come at the outer limits of either barrel.
In other words, there is a very specific requirement to be met and 4150 does it.
I'm also speaking off-line with a bench-rest shooter, who also builds AR-15 rifles, and he seems to think that the additional hardness helps with the rate at which the muzzle "bells out" as higher round counts/rates of round counts increases. This is more prominent with threaded barrels than unthreaded barrels, btw.
That appears to make sense on the surface.
I know from working on aviation steels, that it is much tougher to screw up the lower numbered steels. 4130 is the easiest to work on, while 4140 and 4150 become harder to work without making them overly brittle or wearing out your tools. In other words, if you don't have perfect quality control, 4140 has a better chance of turning out "tougher" than 4150. The additional hardness potential of 4150 requires a higher QC, in other words.
I seem to recall something about heat dissipation superiority of 4150 over 4140.
I wrote "I think" because I am 1) admitting that, not being an expert in some things such as metallurgy, I must rely on the expertise of others, and 2) although I have never once found any barrel failure in civilian usage of 4140 v. 4150, there may be a case of it happening. I still have not heard of such a failure, nor have you provided any such information.
Your response contains its own "I think" on your part. You "think" the military is using the very best steel out there for its barrels. Do you know that for a fact? Although the military has performed numerous and expensive studies of various materials, every decision is a compromise. One need only look at the history behind the M-16's development within the military to see that. Based on my experience in the military, which includes 2000 flight hours with the Navy, I can assure you that there are other times when the military makes compromises. For example, my issued MB-4 flight computer (a type of aviation slide rule for solving navigational problems) had letters and numbers painted on the metal surfaces. Those letters and numbers soon wore off, so I (like every other nav I worked with) bought a civilian version in which the letters and numbers were etched into the surface. The military version was a compromise. The civilian version was a compromise. In my case, the civilian compromise was the better of the two.
Based on my experience in the military, my experience in production management, and my common sense, I believe the military is using the best compromise for its purposes when it demands 4150 steel for its barrels. I also believe that there is probably an absolute best, no-compromise steel for military purposes that the military would not choose because it would be far more expensive than the 4150 that sufficiently does the job. I also believe that the military's purposes do not perfectly mirror civilian purposes, and that the differences warrant thoughtful consideration rather than blind adherence.
Your scotch analogy is flawed because it compares two vastly unequal choices. A better analogy is the difference between Napa Valley wines and Sonoma County wines. Each region produces high-quality, flavorful products, but they satisfy different flavor expectations for the drinker.
But back to the point: If you have any proof that my 4140 barrel is going to fail in my time of need simply because it's not 4150 steel, please provide that proof. Otherwise, you're preferring 4150 simply because "you think" it's better for civilian usage.
P.S. If you think the big guys (or anyone else) will pay even a little bit more for their steel but not pass that additional cost along to consumers, so that it becomes a non-issue, then you and I will have to agree to disagree.
It was explained to me by someone with a PEng in something relating to this - that the metal maintained its strength better when hot. Creating a safer barrel - and one with a greater longevity.
It was in relation to accessory mounting and the like - so I cannot offer anything else other than it will droop less etc.
*I'm a knuckledragger so take this with a grain of salt, all of the conversation was in relation to the droop and subsequnt bolt sheer when weight is applied onto the barrel...
Kevin,
Given that it's "heat related", did your PEng indicate whether or not semi-auto fire would be enough to stress the steel and get to the heat threshold where 4150 makes a difference? I've heard the arguments that 4150 is needed only for FA fire, just wondering if that statement has any merit or if there's a known rate of fire where 4140 enters the not so desirable" zone.