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You a clearly out of your element and off in the weeds as in smoking weed. You have ZERO BASIS for any extraction or bolt thrust comments without any math background. You are just babbling garbage now. The following is a really stupid statement. If you could comprehend statics and the force of friction on an incline you would understand that what you have written below. If you have any analytical skills please calculate the reaward force and compare that force against the force of friction under the load of the chamber pressure. Then tell me how anything moves to the rear when the bolt face is there to stop it. See what I mean it cannot move because the bolt will not let it. The force that seems so real in your imagination when actually analyzed (such as you see in Varmit Al's finite element analysis (FEA)) is miniscule. The taper angle of a standard compared to an Ackley chamber differs so little that the force differences are negligable. What you think is a huge rearward force caused by the side walls of the case does not happen. If you think that this really happens what happens to the rearward force cause by the brass slipping up the shoulder at the front on the chamber. The shoulder naturally gets much larger if the chamber is straighter and the shoulder has a relatively huge angle to create force with. The truth is the bolt can take the force no matter where it comes from. Just blow a primer in any front locking bolt rifle with a nice smooth chamber and see what happens. What happens is the primer leaks and you open the bolt and extract the case because the chamber is smooth and there is taper on the case. >>>The case doesnt "carry" the pressure, it contains it. Whereas with a greatly tapered chamber there is a more pronounced rearward movement of the force because of the taper placing a greater workload on the brass near the head of the case. <<< Sorry bro all you are doing is repeating a 1960s Guns and Ammo Magazine. Go back to Varmit Al's 3 or 5 or 20 times until you understand his finite element analysis. It is not opinion - mine or his. It is just the result of engineering analysis. Case shape counts for almost nothing except for feeding and extraction. If you want easy extraction you want a chamber with taper. Finish of the chamber counts for a lot especially easy extraction. | |||
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. . . and then the X-Die was invented by RCBS. Cases that would usually stretch 4-6 thou every FL sizing would now only stretch 1 thou. (These are my actual measurements mind you with the .308 Win case) Now negating the argument that the Ackley is better on the brass.  | |||
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The fact that you have absoloutly no knowledge of the SIMPLE FACTS that occur during an explosion within a rifle case does not mean that I am making stupid statements, it means you are lacking comprehension and YOU are the one making stupid f$^king statements! If "it (the case) cannot move because the bolt will not let it", (an utterly clueless remark) then what causes case head seperation smart ass? Why dont you backtrack this very thread and read up about headspace. There is a lot of information there that you are clearly lacking. You sit there in your ivory tower and call me stupid while at the same time trying to tell me that it is not possible for any rearward bolt thrust!! You are simply WRONG!! What do you think, that I am implying that "bolt thrust" is going to cause a 1/2" of movement or something, like a bolt will turn to jello? How thick and clueless are you? Have you ever heard of a little thing called bolt set back? If bolt thrust is all in my imagination then what causes THAT? Both bolt thrust and case head seperation occur within something called "acceptable tollerances". Also known as headspace! When you are talking about 50,000 + CUP, the movement that you ignorantly refer to as "miniscule" is certianly enough to contribute to things like case head seperation, bolt set back and it absoloutly does matter! And the movement that you claim doesnt exist is precisley the reason why headspace is such a critical saftey factor in all rifles. I thought EVERYONE on AR understood that until reading your rediculous drivel. You cant answer the question of WHY does an AI case mask pressure because YOU are completly clueless and YOU are the one in over your head! I am still not sure if your obvious lack of comprehension on the matter has allowed you to even manage to grasp that ONE single question I have repeatedly asked yet, you clearly have not answered it! I just love educated idiots who have the gall to look down their noses at others while not even knowing what the hell they are talking about. Had to deal with one like you at work today. I just let him babbel on and make a fool of himself. And it is "internet experts" like you who boldly slander people like Parker Ackley as if you are so certian about yourself when you dont even understand the simple concept of headspace!! What a joke! That fact that you had to go and make this personal speaks volumes of your lack of ability to meet the discussion on an academic level. And Im done trying to penetrate your obvious, self imposed mental block on this issue. Go visit the gunsmithing forum for a while and try actually learning something about the topic. You could start with researching case head seperation in a Savage model 99, or why headspace is important. Until then your feckless replies are a waste of bandwidth. | |||
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Really?  I dont recall ranting about "stupid engineers" or saying ANYTHING about traveling @ high speed.. You clearly have me confused with someone else. | |||
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It is hard to take someone serious who dosen't believe in mathematics. That's what built the world you enjoy. Now do you make a connection?. You are part of a world that believes in dumbing down. eg. The world is only 5000 years old, Global warming is a fraud. It goes on and on. | |||
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Yea, I made the connection, you are taking a political side of a physics issue. How seriously do you expect to be taken? By the way, Al Gore has some oil shares in Iran he wants to sell you.  Dumb that down bitch!Take your political ignorance to the political forum you Dianne Fienstein, anti gun loving pea brain of a troll.  | |||
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I have owned at least 1 case head separating .303 British Lee-Enfield since the time JKF was still breathing. I am very well acquainted with case head separations. With a Lee Enfield they are caused by 5 different issues and I have performed the manual calculations that quantify some of the problems. In that area I am way ahead of you. I very seriously doubt that you understand what happens with a Lee Enfield or the Savage 99. Even if I explained you could not comprehend it but you could not provide a mathematical model of what causes it. | |||
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Stonecreek, I apologize for using your words to illustrate a point to another. I expect you consider yourself done with this subject. SR4759, Please read the above statements. It is a direct response to my question "why does an AI chambering mask pressure signs that a standard chambering does not?" that you in your thick headedness choose to ignore.
Most others understood me completly a long time ago. And it is a darn good attempt to explain IMO. I find nothing in Stonecreeks remarks that I disagree with. Also lets be clear about one thing, the only time I have EVER said that the bolt moves was in your imagination!! Maybe I didnt explain myself worth a darn when I said "there will be a rearward movement of force". But I have NEVER said that the bolt moves. Glad to see that you have finaly figured out that "bolt thrust is a force" though. Are you sure you got the math right on that one? Maybe you had better go back and re-affirm that with your Texas Instrument.. Because it seems to be in direct contradiction with your previous math..  As for me, I kept my calculator in the drawer because "I have understood it as a FACT all along". It seems pretty obvious to me that you simply do not wish to address the question of how an AI chambering is able to mask pressure better than a standard chambering. All you want to do is go off on tangents like chamber finishes, setting up dies and fuzzy math that you have no ability to produce. Bolt thrust will be the same no matter how you set up your dies!! That is completly irrelevant.. I get the feeling that if it came down to sitting at a table and discussing this I expect we would come pretty close to agreeing on most things. You said previously, and I am paraphrasing, something like if one did the math to evaluate the residual effect of of a tapered vs a non tapered case on the head of the case that it would be minimal. Perhaps you should. All I am really suggesting, and the experience of most AI users reflects, that whatever the sum is, it is enough to mask the usual pressure signs at least to a noticable degree. Wether or not your calculator agrees with over 50 years of who knows how many users all over the world, I cant say and claim no responsibility for. I am just stating what most people already know to be true. And if my attempts to explain this phenomena are lacking in your eyes then oh well. I dont need triginometry to know that the world is in fact round. The truth is the truth no matter how you get there. | |||
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Bolts and receivers flex. For anyone wanting to know a procedure to calculate bolt flex, Dan Lilja shows how to do it: http://www.riflebarrels.com/ar...olt_lug_strength.htm The greater the distance between bolt face and locking lugs, the more the bolt will flex for the same load. This is why rear lugged actions, such as the Lee Enfield are hard on cases and case breakage is common in rear lugged actions. | |||
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 Sad thread !  rogerOld age is a high price to pay for maturity!!! Some never pay and some pay and never reap the reward. Wisdom comes with age! Sometimes age comes alone.. | |||
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Despite being the favorite chew toy of many of the posters in this thread, Wstrnhuntr is handling the abuse well. I am, however, going to continue to disparage, malign, P.O Ackley and his methods. It had been a while since I read my P.O. Ackley Handbook, I got it out, and on page 138 there are these “pressure” tests conducted by P.O. This section would fill a super tanker with snake oil. P.O uses a Savage M99 action to “prove” his theories. I think this is again one of those selections that was more than fortuitous. I don’t own a Savage M99 but Jack O’Connor had one. On page 34 of the The Rifle Book, Jack mentions that the Model “99 will handle higher pressures than almost any other lever-action, and because of the solid locking the cases do not stretch to the same extend as they do in the Winchester rifles. I am able to reload my 250/3000 cases without full-length resizing”. I am aware that Savage chambered the M99 in 308 Winchester which is a high intensity cartridge, pressures are around 60,000 psia. I was able to confirm P.O claims that a maximum load of 34.5 grains of Hi Vel #2 pushs a 100 grain bullet 2900 fps at a pressure of 52,000 psia. This data can be found in Philip Sharpe’s “Complete Guide to Handloading”, page 357. P.O states that a load of 36 grains will lock of up a Savage M99 with the standard cartridge, he then rechambers the factory barrel to the “Improved” version. He continues adding powder until the factory chamber is swollen. When you examine load, the barrel carries more load than the action. You can calculate load as chamber pressure psia times surface area. The result is pounds. A cartridge is a 3 inch cylinder, the surface area of the cartridge times pressure distributes far more load against the barrel than the back of the case does on the bolt. You can verify bolt load calculations at Llija’s web page, the base diameter of the case end is somewhat less than an half an inch. P.O loads his improved cartridge at pressures levels that exceed the yield of the barrel and he permanently deforms the chamber. P.O assumes everything is OK because the receiver has not blown. There is no reason to assume that the barrel and receiver will burst at the same pressure, and when they don’t, assuming that pressures are therefore safe, is insane.  Discarding the factory barrel, P.O installs a high strength alloy barrel, which is of course stronger than the factory, and increases the powder charge more till he starts blowing primers with a powder charge of 42 grains Hi Vel #2 and the bullet is going 3400 fps. He still claims no extraction problems and therefore all this wonderfulness is due to straight cases. Wish I knew just what pressures he was operating this cartridge but it was high. I don’t know why this one experiment of his did not produce sticking cases, but he did stack the odds by using an exceptionally strong action. I don’t really care that the action did not lock up as it does not prove that he is working at safe pressures for the case, action, or barrel. It would have been more fun had he tried these mini nukes in a Remington Rolling block, but all Ackley proves is recklessness. Ackley does not know action limits, does not know the pressures his cartridges are operating. O’Connor has a section in the Rifle Book about wildcat cartridges. On page 260, he writes “A leaking primer generally shows that pressure are up to 70,000 psi or more. A blown primer shows pressures in the neighborhood of at least 80,000 psi.” This is consistent of tests that Phil Sharpe documented on page 238 of his book "Compelete Guide to Handloading" in the section “Important Loading Notes” . As Mr Sharpe says in this section “Many of the boys playing with super-hot wildcats are regularly shooting proof cartridges” . This is how Ackley gets those velocity increases, by shooting loads that were equal if not higher, than factory proof loads. This is not safe, it is reckless. As O’Connor says, “Pressures of many wild cat cartridges run very high. Some experimenters conclude that if their rifles don’t blow up with a blinding flash they have nothing to worry about. P.O. had the same access to pressure testing equipment as did O'Connor and Sharpe, and he had more resources than either of them. He could have made a pressure gage as he had a machine shop. P.O never publishes any pressure data, if he had, it would have shown what he was doing was unsafe. His book remains an artifact of an interesting, wild and wooly era. But I am not putting any faith in Ackley's conclusions about his cartridges. | |||
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Well I am glad to see that the main stream gun press is starting to question the claims of P.O Ackley and the so called reduction of bolt thrust Ackley claimed. Just yesterday I received my Oct-Nov 2013 issue of Handloader and in it was an article by John Barsness on “Bolt Thrust and Related Myths” . I agree with Mr Barsness that Ackley cases do not reduce bolt thrust and that the tests in Ackley handbooks are flawed. While Barsness refers to tests by others, he does not present test data of cartridge thrust, and that would have been a significant contribution to the literature. He does state conclusively that case shape does not reduce bolt thrust, given the same case head and combustion pressure. Mr Barsness fires lubricated cases, as do I, but I have not found data to substantiate his claim that oil lubricity goes away at pressures above 10,000 psia. I cannot imagine any engineer designing a bearing to carry a contact load of 10K psi, but I don’t know the limits of oil film strength, so this could be a probable. | |||
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I think you can refer to all of the writings of Ackley, O'Connor and others and prove anything you want or prove the opposite. None of them conducted designed experiments. None of them mathematically analyzed their work. Sort of like the fundamentalists that quote one thing from the Bible one day and the opposite on another. They did not indicate their actual pressures, sizing technique, chamber finish or presence of lube in the chamber most of the time. They probably did not know the pressure or the chamber finish. Analysis of bolt thrust and case friction in the chamber has been done by finite element analysis a tool that is the world standard for engineering analysis. To claim that AI chamber shapes do much of anything goes against the laws of physics and that is supported by FEA. Simple analysis of the taper angles by trigonometry can tell you to not expect much. | |||
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While this thread has been an entertaining read at times it has also been informative at others. I believe that every serious handloader knows that the length of the case (from the shoulder datum to the head) must be very close to the length of the chamber to prevent case head separation and that a gun with a chamber that is too long can still be fired safely as long as the cartridge is formed to the chamber and that length is maintained in the loading operation. I thought we were all aware that the case expands to the walls of the chamber upon firing and that if the cartridge can be pushed forward at the point of firing then the head of the cartridge is away from the bolt and the case will stretch at the head toward the bolt face - which, if done enough, causes head separation. If we ignore the sizable friction between the case and chamber wall the bolt thrust is a simple calculation of the chamber pressure times the area of the cartridge head. The bolt and action is designed to operate within that load with a failure safety limit of at least 50% or to be more exact, if the load could be doubled it would result in failure of the connection between the action and bolt. The pressure in the case extends in all directions equally but the bullet moves down the bore, the case expands to fill the chamber and the bolt keeps the rear of the chamber in place. The amount of taper, if the head spacing is correct between the cartridge and chamber, has so little effect on the thrust at the bolt that it should be considered nil. The frictional effect of a case with less taper is present to a greater degree than any angular thrust simply because there is more area for the case to be pressed against. If the headspacing was not correct (the case was too short for the chamber dimensions) the AI cartridge would exhibit more tendency to have case head separation than the tapered case because the case would be pushed forward and held there more quickly than the tapered case. The bottom line is that if the cartridge fits the chamber it matters not whether the case is tapered or straight. The same head diameter at the same pressure will produce the same force against the bolt face and as long as that pressure is within the working load for the design nothing bad can happen. Speer, Sierra, Lyman, Hornady, Hodgdon have reliable reloading data. You won't find it on so and so's web page. | |||
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