Okay, we have multiple problems here.
If you read the report it came from or my original post where I posted it, you would know that it is NOT an M1 gas system (and we would know it too, if you hadn't cropped the header information off). That graph is for a T44 with a gas impingement system.
I was about to agree with you on this, that is, I don’t know the impingement gas system from the expansion, but then I looked over my graph, and it is the “Garand” impingement gas system. And surely you over looked what equipment was used in the test. Later on that.
If you are concerned about me taking your image and using it, you know I have had you on “ignore” for a couple of years now, told you I was not interested in reading your posts, or you mine. And I and have not noticed a post of yours showing this kinematic pressure curve. Because you are on my ignore list, I did not know you were commenting on my post, until I noticed Gunny’s outburst, and then I knew the thread had gone twisted.
Since I don’t know when you started posting this image, here is an example of me using it in 2018, might be earlier, I am not going to spend hours looking for the earliest use of it.
https://thefiringline.com/forums/sh...ighlight=residual+blowback+effect#post6576524
Neither of us owns the copy right. I water marked mine in case Bart B (Bart Bobbit) used it. Bart Bobbit used to post here, and his old saw was that the 30-06 could not shoot straight, which is mentioned in this thread:
https://www.thehighroad.org/index.php?threads/exposing-some-internet-myths.346192/
I got into a debate with Bart Bobbit, and I posted Camp Perry NM test targets with two hundred round dispersions of NM 308 and NM 30-06. There was not much of a difference at 600 yards. The week that post was created, the target picture disappeared from my photobucket account. I really do not care if people use these images to further knowledge, so I left my account public, incase someone wanted to copy and use. But, I never thought anyone would delete images. After that, I made my photobucket account hidden, and all subsequent photo albums private. And what do you know, almost a decade later, Bart Bobbit was using a truncated version of that picture here!..
Bart B seemed to be a knowledgeable shooter, read enough of his material, every so often, what he claims, is impossible. Or just has to be a flat out lie. That is why I also put him on ignore.
I don’t catch all flat out lies, or lies of omission, but when I come to the conclusion the poster is not mistaken, but actually lying, then I don’t want to ever read material the guy posts. Nothing a liar posts can be trusted to be true. There are pretty sharp people here, and they were giving Bart grief for some of his dubious claims, and I have not seen him for a while.
Okay, we have multiple problems here.
1) Where'd the M1 Garand gas system graph come from?
Like I said, I have had you on ignore for about two years, I had no idea you were using these pressure curves. They were out there, in the open literature. There was a time before 911 when a lot more, unclassified Government material was open source, but after 911, more and more information has been pulled behind the firewalls of that Government and Government Contractor only, DTIC website. Government goes through this, for a time Daniel Patrick Moynihan was beating it back, but he is gone.
Did you read the report and notice what was used as a test fixture? And, is a 308 Garand a Garand?
As a comment, nitnoidism is the life blood of the web. All these Nitnoid experts, showing off their nitnoid knowledge, primarily to put others down with their pedantic knowledge, it is the life blood of forums. When I was writing my post, I was more concerned with explaining how gas guns work, than getting into a nitnoid history of the Garand and all its variations. For example, there never was a 308 Garand, the military used the 7.62 Nato cartridge, so the military cartridge was never called 308 or 308 Win, right? And the 30-06 Garand was never called the 30-06 Garand by the military, the receiver heels are stamped Cal.30 M1. And from what I remember, the official literature never called them Garands just rifle, cal 30 M1. However, this military nomenclature is not well known, and it would take paragraphs of nitnoidism to explain this, bore the reader, and so for simplicity, I call the rifle 30 cal M1, a “Garand” and call the 7.62 Nato version, a 308 Garand. Because most people know what a Garand is, and it gets to the point, is simple, even though a nitnoid would rightly say, “there was no such thing”.
Anyway, is the 308 Win Garand a Garand? I looked on my hard drive for the Ackland AFB 7.62 mm Garand I handled, but I only took pictures of the match modifications, but if someone does not know, there were military Garands in 308 Win. But do you accept a 308 Garand as a Garand? What is a Garand anyway?
Springfield Armory calls these M1 Varations:
https://www.nps.gov/spar/learn/historyculture/m1-variations.htm
Notice how many of the use the “Garand” gas system. Is the Tanker Garand, a Garand?
And these are experimental rifles by John Garand:
https://www.nps.gov/spar/learn/historyculture/experimental-rifles-by-john-garand-1919-36.htm
Now I would agree, that the pressure curve of a 30-06 Garand gas system would likely be slightly different than the 308 Win version, but the only difference in the gas system of a 30-06 and 308 Win Garand, is the size of the port hole. I am sure a nitnoid could stuff a Galaxy down the difference in port hole sizes, and revel in the points he was scoring.
(By the way, I don’t blame you for all the bite marks your guard dog made. Normally, he is a good doggie, tries to be helpful to others. I did not mean to get his blood up.)
And then, did you read the details of the report? Lets get into some more nitnoidism. What receivers were used in the early “long action” T44’s? You will get a bonus point for correctly identifying the model. However, even if you reveal it, who the heck knows about that model? I had to look it up, because it is so rare. It is a rifle designed by John Garand, and it was manufactured at Springfield Armory, and I suspect you know all the parts that were common between it and the rifle 30 cal M1. Now, you will get real bonus points, and many thanks, from Garand nitnoids around the nation, if you search your Government databases and identify at what receiver serial number, the T44’s went from the “long action” T44’s to the short action T44’s. Up to the point the short action T44’s were introduced, all the T44’s used in the tests against the T47’s, and the FAL’s, etc, were those earlier model “Garand” receivers, modified to the purposes at the time.
And, what gas system, and barrel was used on the T44 test fixture rifle, used to produce the impingement kinetic pressure curve? I am sure that it was an honet mistake to over look that the gas system was identical to the rifle 30 Caliber M1. The barrel used, was a 7.62mm Garand barrel, which I am sure, was something easily overlooked. After all, who actually reads this stuff?
Now, I could have gone further and deeper into nitnoidism, in the post you are questioning, but would anyone care? At some point, you have to simplify and get on. Is it not easier to just describe the curve as a Garand gas system diagram and not use the words, gas impingement, T44 and, T93E1 ammunition. Who the heck knows what a T93 round is, anyway?
Honestly, I can’t keep track of which gas system is called impingement, and which is expansion. The distinctions are artificial anyway. Other than nitnoids, who is enforcing the lingo? I think of them in terms of “the Garand gas system’, and the “M14 gas system”. And a nitnoid might argue, the curve of the gas expansion system cannot be the M14 gas system, because the M14 did not exist at that time.
All of this is tedious, nit picking, adds nothing to nothing, and surely takes away from what I was trying to do, that is explain how a gas gun works.
2) You show a Caliber .30 Carbine pressure-time curve, then discuss its interaction with the gas system with a totally different different cartridge.
So, let's look at 7.62mm NATO, and the T44 gas system graph you posted, I won't bother to post the pressure-time graph for 7.62mm as I have done so before, and you probably already have a copy.
From the T44 graph the bolt starts to unlock at 2.3 ms. The 7.62mm NATO pressure-time graph (that is the mate to the Carbine one you show) has the chamber pressure at 2.3 ms as 375 psi. So, the force pushing the case out of the chamber is, at most, 65 pounds, most likely less as there will be some friction between the chamber walls and the case.
We can calculate the acceleration and velocity of the case (assume a friction-less case to make life simple) and compare the case velocity due to gas pressure and the bolt velocity and acceleration from the graph. If you do, you will find the bolt has about 50 to 100 times the speed advantage.
So, the extractor does extract the cartridge case.
Let me say, I have not seen your pressure curve charts, but, if you are putting them out, that is great. Really, not being snarky about this. I believe in the increase of gun performance and design information in the public domain. It is my opinion that an educated gunsociety is better for the knowledge. Lots and lots of function problems, and safety issues, could be avoided if people understood the mechanics of their weapons. What data is outside your Government firewalls is piecemeal and fragmentary. And I will admit, I don’t have the full picture. I, along with many others, are piecing together the fragments that somehow, made their way outside the Government restricted databases, and trying to make sense of the data, and applying their own theories about how these things work. Even less falls out of Corporate vaults, if you ever worked in industry, everything is proprietary. Industry wants ill informed consumers who make ill rational purchases.
As to the residual pressure curve, the author of Random Shots, Roy E. Rayle, states on page 186
“After unlock another action occurs which can impart five to ten per cent more energy to the recoiling rod and bolt. This is blowback due to residual pressure in the spent case Significant pressure is maintained in the case for several millisecond after unlocking during the blow down period. This provided a force to the rear whose influence can be noted in the velocity curves of both systems (expansion and impingement).
I am going to claim, that breaking the friction between case and chamber is good for function, and easier on the extractor. If friction between case and chamber defeats the residual blowback affect, then, the extractor is going to have to pull the case out of the chamber, and in time, that will reduce the lifetime of the extractor.
4) I have read every report the US Army published on the development and testing of the FN FAL (T48), and I have not come across this nugget about oiled cases. Could you please cite the reference. The only thing discussed about the extractor was the original one piece extractor with a wire leaf spring was not acceptable because a) it came out to easily, and b) the grip force was insufficient to hold the rim during automatic fire. Extractor life was never mentioned.
Not everything is in the official reports, on the Government and Defense Contractor only DTIC report base. By the way, look how many of those reports were done by Larry Moore. tee hee-hee
From the book mentioned previous, page 64,
“near the end of the line Colnel Dubia rubbed his finger over some cartridges, and noted a light, but definite trace of oil, which appeared to come from an oily belt used to move th cartridge from one point to another. Colonel Dubia was able to convince the FN authorities that this might be the reason why we where having so much trouble with extractor failures in the American rifles, which FN was having little difficulty. FN agreed to run some testes with cartridges completely free of oil, and soon discovered extractor failures did go up”.
Mr Rayle was directly involved in th M14 and FAL program, along with many other weapons. The book is worth a read, particularly as it describes a lost world from that of today’s Government and Department of Defense. At one time the Army had its own manufacturing facilities, arms designers, material experts, production experts, and what they could do, the expertise they could bring together, to analyze problems, make changes, make the parts now, run tests on those parts now, to solve firearm issues now, is gone.
I did look on the FAL web site and found a shooter who said steel case ammunition had broken a couple of his extractors. I did find those that claim Russian weapons are designed to rip the round out of the chamber with the extractor.
https://www.pewpewtactical.com/brass-vs-steel-ammo/ Maybe so, Russian design philosophy is different from American, and their weapons are amazing designs. However, as someone who has worn out extractors, had extractors break, and replaced broken and worn out extractors, in my opinion, it is best to reduce as much as possible, stress on the extractor. And having experienced it before, a worn extractor will remove the case from the chamber, but that same round will fall off the breech face, and cause a jam because extractor tension was insufficient to keep the round on the bolt face. If there was such a thing as a frictionless case to chamber, and the only function an extractor had to do, was to hold the case against the bolt face, extractor life would be very long. And that is another reason I advocate lubricating steel cases, to reduce case to chamber friction.
3) Lt Col. George Chinn's book is a great source of information, especially if you are planning to sit down and design an automatic weapon. However, if you have to be careful pulling to many of his "rules-of-thumbs" or extracting graphs as examples of "proof of your point of view". The point of that five volume set was to assist engineers in designing automatic cannon for Naval aircraft, as the Hispano had less than stellar performance. All of the graphs, and examples in the books are based on the Navy's 20mm, Mk100 ammunition, which isn't even the same 20mm ammunition used today the M61, and other modern 20mm cannons. Forced extraction of a 20mm cartridge case, that weighs 1/4 pound is very much different from extracting a case that weighs 20 times less.
I will say, we owe Chinn a great debt. Who else is putting out the principles of machine gun design? The series is very non mathematical, very concept orientated. That generation thought in terms of “
we are all in it together”. They would never had understood a generation where 70% care not about spreading disease to others. Based on my study of post WW2 history, technology development for small arms had pretty much reached a period of dimensioning returns. Designs have further coalesced around a few mechanisms, the major advances since WW2 have been in manufacturing and materials. However, post WW2 there was a real need for fast firing machine cannons for even faster airplanes. Weapons such as the Oerlikon were the fastest single barrel guns of WW2, but even multiple Oerlikons could not put enough lead on target to down a jet aircraft. It was in Chinn’s period the Vulcan machine gun was designed, and as jets got faster and faster, even that could not put enough lead on target, and eventually missiles took over as the primary weapon of jet planes, and air defenses. Artillery also hit a peak in the 1950’s, and the emerging technology of missiles, killed off the big guns. As you know, multiple rocket launchers can saturate a target hundreds of miles away, and big missiles can hit targets on the other side of the planet. Something that fires a shell only 20 miles, while that is still lethal, it is clearly out classed by something with a range of hundreds of miles. China has a carrier busting missile whose range is greater than fighter jets. I would say, they are sending someone a message about maintaining a safe sailing distance away from their mainland.
5) Properly designed, and manufactured steel cases will not drag any more than properly designed and manufactured brass cases. The problem is: "Is most steel currently available properly designed and made?"
I am certainly not going to vouch for the quality control of either Chinese or Russian ammunition. Chinese ammunition disappeared quickly after the Bush ban of 1993. Considering that we are all using Chinese built computer equipment, I would believe that the Quality of Chinese ammunition would be very good, if we could only have access, but that would reduce profits for American Plutocrats. Russian quality control is probably more of a matter whether the work force arrived sober that day. Russians drink like fish.
However, there are a number of outside sites that address steel case ammunition
Steel-Case Ammo: Bad For Your Gun
https://www.shootingillustrated.com/articles/2018/10/23/steel-case-ammo-bad-for-your-gun/
Is Cheap Steel-Case Ammunition Safe to Use?
https://www.nrafamily.org/articles/2021/4/1/is-cheap-steel-case-ammunition-safe-to-use
I am going to be nitnoid about this statement in the article.
Steel-case ammo was first made in Russia and Germany during World War II to save production costs, because steel is cheaper than brass.
The Germans made billions of 8 X 57 mm steel cartridge cases in WW1. The also coated it with a lubricant to improve extraction. This is almost unknown in the US after the war, and it may be because the US did not occupy the country as it did after WW2.
The Truth About Brass vs. Steel Ammo
https://www.pewpewtactical.com/brass-vs-steel-ammo/
When to use steel cased ammunition?
https://blog.cheaperthandirt.com/steel-cased-ammunition/