The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Re: 3030 Ackley Pressure Ring MeasurementsGo | New | Find | Notify | Tools | Reply | |
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Quote: Hey Rookie, That is correct. Quote: Don't need to know the hardness. That is because the Multiple Million Dollar Factory Labs have established what the MAX Load they feel comfortable sending out "for rifles of ALL ages" is acceptable in the Cases used to establish the Benchmark Standard. Nothing complex or confusing at all, unless of course you are a Rookie.  Quote: You actually got that correct, which surprises me. Apparently "some" of what I've posted is sinking in. Quote: Also correct. It is a simple matter of performing PRE - correctly - and following a good Procedure. You are sure doing good for a Rookie. Quote: Nice resume for a Rookie. Now do tell us, "What exactly" is Deke's rifle going to tell him?!?!?!?!  | |||
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Quote: Hey Rookie, I'm ready to learn. Which part of the Case do you "think" is going to wear out? Can't be "expanding Primer Pockets" or the Casehead(for CHE) because Deke should not be running at a Pressure Level high enough to expand them. How `bout this, just tell me which "part" of the Case you are talking about??? | |||
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Quote: Hey Deke, Once you do that, it will for absolutely sure tell you if you are operating at a Pressure that is too much for the Marlin 336. Just re-develop from below. Once you do that, you can than take the Benchmark Standard and develop Loads for the H4895. I like it real well too. ... There is one more thing you can do to increase the Velocity and reduce the Pressure. It is to.... Huuumm, maybe we should let the two Rookies(denton & eldeguello ) have a chance at "guessing" what that would be. I'll email you about it when I can get back into Hotmail. It was acting goofey again this morning.--- Hey AC, My PM is cut off, so I can't use that. | |||
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Deke, A long and interesting thread. I dont think I could add much to it but I have a couple of observations. The lever-action chambers that I have looked at are slightly egg shaped at the base of the cartridge to help feeding. As you measure the pressure ring on your cases rotate the case and take at least three measurements. You should see that there is one spot larger than the others. I have reamed four .30-30 Ackley chambers, three Winchesters and one Marlin, on each of these the reamer did not cut a full circle in the chamber right at the base. The thing that might negate establishing a PRE baseline from factory cartridges fired in the standard .30-30 chamber prior to Improving is that all new 30-30 brass I have measured has been undersize. Most measuring .417" or just slightly larger. The brass does not expand to fill the chamber at factory pressures. New brass fired with a full pressure load and then full length resized will generally measure about .421". I agree that .422" is all the case expansion I would care to see. PRE measurements used only to help establish a stop point and used in conjunction with chronograph data is a good cross reference when working with an unknown cartridge. As Ken Waters pointed out in his article PRE is not pressure. The .30-30 Improved data shown in the Ackley Handbook for Shooters and Reloaders was developed for Ackley by Robert Hutton. This was published in the June 1961 issue of Guns & Ammo. The data listed by Hutton is the exact data in Ackley's book. Hutton was looking for a long range target cartridge and used a long barreled FN Mauser to collect the data. This data was not intended for use in lever action rifles. The problem with the Ackley Handbooks is that time has blurred where a lot of the information came from. I agree with others who have told you that IMR 3031 is too fast for this application. There are better powders available for the .30-30AI today. I think 37.0 grains of IMR 3031 is a maximum load for the 150 grain bullets in a modern lever action rifle. AC has several very interesting posts in this thread. I have a Winchester M-94AE with rebound hammer converted to .30-30AI. AC's observing shearing of primer material that has extruded into the firing pin hole is not something I have seen, thank goodness. It does seem logical that the rebound hammer would allow this at high pressure. I have seen primers extrude into the firing pin hole on the Thompson Contender with high-pressure .223 handloads. Tailgunner has pointed out that RCBS load is a very handy program for figuring case capacities. The cartridge designer function allows you to alter cartridge dimension and estimates the change in capacity. His estimate of 47.7 grains of water to the case mouth is pretty close. I measure 49.8 grains of water to the case mouth in an R-P .30-30 Improved case that has been fired but not sized. AC measured 47.1 grains of water in a standard R-P .30-30 case. I measure 46.5 grains, again from a fired un-sized case, so we are pretty close. Another good feature of the RCBS Load program is it allows you to vary bullet-seating depths while estimating the changes in useable case volume. AC has wisely suggested that you consider Hodgdon 335 or 4895 for the .30-30 Improved. In truth your powder search could start and stop with either powder, depending on whether you prefer ball or extruded powders. Our velocity goal for the 150-grain bullets is 2,500 fps in the 20" barrel and either powder meets the goal in hot weather without alarming pressure indications. This also allows our ammunition to be interchangeable between rifles. IMR 4064 is an excellent powder for the cartridge but you begin to run out of room. Winchester 748 and Hodgdon BLc2 will show early warning signs of high pressure on hot days. In cool weather either powder generates high velocity and good accuracy in our rifles. I have obtained the highest velocities with reasonable pressure indication using Hodgdon Varget and Alliant Reloader 15. 2,500+ fps with 150-grain bullets and 2,300+ fps with the 170-grain bullets are easily obtainable in the 20" lever action rifles with what appear to be reasonable pressure indications. I again urge you to take to heart the warnings about IMR 3031; it is a bit fast for the standard 30-30 on hot days. There are better powders available. | |||
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Quote: That's extremely useful information. It explains why Ackley's load is so hot... probably just fine in a bolt action. | |||
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Quote: If anyone out there in NetLand is near denton, pllllllease take him some Mylanta and a few packs of Rolaids. As amazing as it may seem to some, all of a sudden another person using PRE to his advantage pops up in this thread. And he even knows to "rotate the case" when measuring PRE. Outstanding!! ... HSGS = Reloader's Pyrite(aka Fool's Gold (just for denton! ) | |||
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Thank you for your concern, Hot Core, but I am not suffering in the least. PRE and CHE both royally flunked an industry standard test for repeatability. They do not give you the same dimension for the same pressure. Their repeatability is poor. As a measurement system, two different tests say that they contain more random error than information. Your idol, Ken Waters, clearly said that strain gages are superior to PRE. His only objection was that they cost too much. Now that modern design has solved the cost problem, what do you have against moving to the system that has, by experiment, been shown to be far superior, and which your idol recommended? And, by the way, since your PRE system (and apparently yours alone) is calibrated, how about giving us some PSI data for your favorite loads? Can't? Maybe your claim to calibration is just a little shakey... or a lot. And can we or can we not use commercial ammo as a limit sample? You have said that we can, and you have said that we cannot. Which is it? You can't have it both ways. You're not John Kerry, you know. And if Deke follows your advice, and blows up his rifle, what are you going to tell him? Are you going to tell him that one of his eyes was just in the way anyway, and that he's better off without it? Don't you think it is time to start clearing up your pile of self-contradictions and totally absurd, unsupportable assertions? As always, you have no facts, no figures, and no physics. You just have an opinion, based on an opinion that you read somewhere. | |||
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Quote:Quote: Hey Rookie eldeguello, You are going to have to speak up a bit. I'm having a difficult time "believing" you know something about this. Which "part" of the Case you are talking about??? --- Did anyone get the Mylanta and Rolaids to denton??? | |||
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Hot Core, since you have just led Deke to use a load designed for a 60,000 PSI bolt rifle in a 38,000 CUP lever rifle, and have totally failed to detect this extreme overload, I would be very cautious about calling anyone else a rookie. You have just had a very spectacular and public failure that could have destroyed a rifle and killed or injured a board member. | |||
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Denton, I don't mind (in fact I am a benefactor of...) this spirited debate. However, I have to step in and clarify that HotCore did not lead me to your last assertion (38gr of IMR3031 w/150gr bullet, leading to a pressure that nobody knows, but a couple have done their best to quantify). I chose that load based on Ackley Vol 1 as a way to find a PR stopping point. I thank the good Lord above (I do pray when going into unchartered waters and attribute my good fortune again to the good Lord above) that the rifle did not blow and am still puzzled on the best way to detect excessive pressure in this relatively low pressure cartridge. Later, Slim clarified the origin of the load I used, saying that it was meant for a different rifle and to back off to 37gr. ASSCLOWN, would you be kind enough to calc pressure for 37gr IMR3031 @ 2560fps, PR=4.205", PRE .0022"? As far as buying the strain guage, it cost as much as I paid for the rifle, but certainly less than a glass eye (or worse....), but I am not there yet. Working with a slower powder (H4895 being my first choice) is still the plan, but first I have to be able to detect excessive pressure. Last, but not least, what is the pressure that a 3030AI will safely operate at in a Mar336 (keep in mind that the straight wall design produces minimum bolt thrust - proven by yours truly still wearing the same pair of sunglasses  )??????Deke. | |||
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Deke, I stand corrected, and retract the inaccurate portion of my statement. Some of us were raising warning flags, but I think it was Slim's info that really nailed it. That's what I call a useful post: Useful information, and a solid source. I do not know the answer to your dilemma, but maybe I can help put some boundaries around it. Marlin makes a stronger gun than some. In the Hodgdon reloading manual, they list loads up to 40,000 CUP for the Marlin 45-70. So I think you have a little more leeway, just because you have a stronger gun. 40,000 CUP is about 42,700 PSI. (38,000 CUP is about 39,700 PSI.) I do not think a strain gage is appropriate for your rifle. If it were, I have a second unit that I would gladly loan you. But I don't think there is a good place to mount the gage. My tests confirm what every other test I know of says: PRE is not sufficiently repeatable to be dependable. Note that it just failed to warn you that you had a dangerous load. Of the available remaining alternatives, I suggest you use one of the pressure predicting reloading programs. I have no experience with them, but Dutch tells me that they are quite accurate. That would be my first choice. I think the other choice is to find a load with an appropriate powder, and load it up to the point that you get the same MV as a standard 30-30, and then go up from there. You probably get 100 fps because the Marlin is strong, and you probably get 100-150 fps because of the extra capacity. So, in my SWAG, 200 fps over book is probably safe, and 250 is really at the red line. But I am quick to point out that that is a SWAG, and only a SWAG. I would consider that a second choice. AC and I were posting at the same time. Opinion bows to analysis, and AC is providing an analysis, which is very likely better than my opinion. My only exception is that PRE is unreliable, unless you average many cartridges. Maybe I've known Clark too long, but 2,000 PSI more or less doesn't worry me much. For one thing, the old CUP system can't reliably repeat within 1,000 PSI, and we lived with that for a long time. Anything that gets you that close is probably going to be alright. | |||
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Deke, I'll get the pressure data crunched in a little bit and post it back here. I think it is still gonna be pretty high. I would recommend reducing you load to the point that your PRE does not exceed 0.0015". Quote: The issue isn't bolt thrust (at least it isn't with a Winchester which is were ALL my experience lies). The lever action carbines suffer from two "problems". 1.) Rimmed cases which can withstand relatively massive pressures without failure. Far greater pressure than like sized rimless cases. 2.) Relatively thin barrels and SMALL shank threads! Meaning the barrel ain't too aweful strong. It is the barrel which will fail in an over-pressure event. It is actually weaker than your brass. To answer your question better I need to know the shank thread size of your Marlin's barrel. I apologize but I do not know what size threads a Marlin 336 uses (I know Winchester uses a 0.809" X 20 thread on the M94) From past experience though, I have deduced that barrel yielding COULD begin to occur at PRE measurements of 0.0019". Therefore, for safety sake I would recommend staying down around 0.0015" Reference my post "Some Insight into PRE Measurements". It isn't complete but I did have the Winchester Big Bore M94 on there. Unfortunately, I am on the road and cannot run a simulation for about a week. ASS_CLOWN | |||
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Quote: Hey Deke, Thanks for clarifying that for the rest of the folks in NetLand. I seriously doubt that denton will "get it" even with your post. I'd told denton earlier this year I'd do my best to avoid directly responding to any of his (questionable) questions (in an attempt to "help" lower his stress level). After your post, it is probably time for another round of Maylox and Rolaids for the Rookie who never allows "Facts" to interfere with one of his posts. Does anyone know if denton can order the Mylanta in a 55gal drum "take home" size??? HSGS = Reloader's Pyrite(aka Fool's Gold) | |||
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Deke, Per your request: Quote: I get a maximum chamber pressure of ~ 76000 psi For the this load: Quote: I am calculating a maximum chamber pressure of ~ 77,500 psi. I actually prefer to use the barrel deflection equations (your PRE measurement of 0.0022" in other words) as I feel they are more accurate. I cannot do that till Thurday of next week. I will though if you want me to. I would expect to see approximately a 10% reduction in pressure for equivalent powder charge weights between IMR3031 and IMR4895 (I'd expect that for H4895 as well). The muzzle velocity will likely take a dip though along with the pressure. Like I said, if it were me I would back off to a PRE of 0.0015" and be happy. At least that level oughta keep all your fingers and eyes in their current places/condition. ASS_CLOWN | |||
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Denton, The PRE did not fail to warn me. I know this is a long thread, but if you read back you will find that I was loading Ackley's load in an attempt to find max PR measurement and really was not using PRE method yet. If I use the PR measurement I got from the 38gr load it would be .4207" at which time I would use it to judge for the future. However, some say that is TOO hot. I have also realized that I may need to use some of the same brass from the factory ammo that was fired in my factory chamber (I bought other R-P brass in bulk) to reestablish my PRE. ASSCLOWN, I have no idea about the shank thread size of my Marlin. Can you explain how I could get that for you? Deke. | |||
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Hot Core, I have decided to do everyone a favor, and give each of your unfounded statements and contradictions a number, so you can just post them that way. If you will just use these numbers in future posts, it will save a lot of space, and a lot of time for the rest of us. For the contradictions, you can just use the suffix "A" when you are on one side of the issue, and "B" when you are on the other. 1. Standard list of Hot Core fabrications, unsupported by any known facts or credible references--- 1.1. Mounting a strain gage on a rifle will spoil the accuracy. 1.2. You need a CMM to measure the ID and OD of a chamber. 1.3. Mounting a strain gage will rust your rifle. 1.4. Strain gage systems cannot be calibrated, and the results are just a guess. 1.5. PRE is completely repeatable and reliable. 1.6. PRE is calibrated. 1.7. Claims to have 20 years of experience with strain gages. 1.8. Claims that strain gages don�t work outside a laboratory. 2. Standard list of Hot Core self-contradictions� 2.1. Claims that you can, and that you cannot use factory ammunition as a maximum pressure reference. 2.2. Claims that you need SAAMI standard ammunition to calibrate a strain gage, but that you don�t need it to calibrate PRE. 2.3. Claims that you cannot use chamber dimensions to calibrate a strain gage, but that you can use brass dimensions to calibrate PRE. 2.4. Claims that he gets four significant digits measuring brass with a micrometer, but the rest of us can�t get three when measuring a chamber. 3. Most childish Hot Core behavior� 3.1. Resorts to name calling and ridicule when things aren�t going his way. < !--color--> Just to be complete, I have also compiled a catalog of items that have are supported by data and credible references. 4. Actual experiment says� 4.1. Strain gage systems are very repeatable, and the one I have tested is on a par with equipment currently in use by people who write reloading books. Two cartridges subjected to the same peak pressure give you very close to the same peak reading, routinely. 4.2. Strain gage systems are easily calibrated, and, once calibrated, they routinely produce peak pressure readings that correspond with the expected pressures of commercial ammunition. 4.3. PRE and CHE are very non-repeatable. Two cases subjected to the same pressure produce the same dimension only if you are very lucky. 4.4. Details of how to replicate my experiment have been posted, for anyone who cares to try it. You can love it, or you can hate it. The data don�t care. 5. Ken Waters actually said� 5.1. PRE is inferior to strain gages and to CUP. 5.2. PRE is a relative system only. (Relative system = not calibrated.) 5.3. Speaking of PRE, �...no such system of judging pressures can reveal the actual pressure in pounds per square inch or copper units of pressure.� 5.4. PRE is not entitled to use the term �reading�, because that would imply a precision that isn�t there. CUP and strain gages are entitled to use the term. 5.5. Ken Waters� article does not mention any meaningful test of PRE reproducibility. If it�s untested, or unsupported by analysis, it�s an opinion. That�s all that Ken published, an opinion. Opinion bows to good analysis, and good analysis bows to data. Data bows only to measurement system analysis, and I did perform that. We do not have to speculate about the relative merits of PRE and strain gages. We have data, and the results are clear. The standard deviation of the random error in the PRE system is 6,800 PSI. The standard deviation of the random error in a good strain gage system is 667 PSI. Published piezo data runs around 1,366 PSI and the copper crusher method runs about 1,827 PSI. Smaller is better, of course. < !--color--> | |||
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Quote: 1) Ackley pointed out that lever actions seldom fail, their thin chambers do. 2) Ackley's experimemnt with removing the locking mechanism and shooting with just the lever and his hand holding the action closed neglects the interaction of an action and the brass stretch [to show the advantage of 30-30AI], as they have much lower compliance than a man's hand. i.e. The action could take a real beating to which the hand is immune. 3) I have calculated the difference due to the change in angle, and it is small. link to my 30-30 Ackley angle calculation | |||
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Quote: Hey Denton! Hotcore's mind(??) is made up! Please stop trying to confuse him with the facts! | ||
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Clark, The other interesting point about angles is that it ISN"T just the outside angle that needs to be considered. The brass has an internal draft angle as well. It is the interaction between the inside case wall taper, which the pressure is being exerted against in a Normal (meaning 90 deg for those that aren't up on their physics) fashion. The reaction forces of course are acting on the outside taper, again normally. Since the angles aren't the same, neither are the resultant forces which are created in the radial and axial directions. This interaction of internal pressure derived force and external reactive force determines just how much the case stretches. So the aforementioned internal/external interaction times the spring rate of the case (a non-constant since the case wall section and radial stiffnesses are not constant) determines the thrust force exerted against the bolt. All in all, a rather complex problem. IF you were motivated enough to "work the problem" you would arrive at the same conclusion that you mentioned in you referenced link. That being, case wall taper has LITTLE effect on bolt thrust! The forces generated by case taper, within the range of MOST commercial cartridge designs, is insignificant compared to the other forces at work. It does though, seem to help sell books! ASS_CLOWN | |||
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Quote: Amazing what can be "proved" if you neglect a physical anchor, isn't it? Just noodling.... As the case yields, and contacts the chamber wall, it has a large amount of force acting on it, from inside the case. Is the coefficient of friction between the brass and chamber enough that the case, except for the head, is momentarily "pinned" in place by force and friction? | |||
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Denton and AC, It is like the problem of standing on a slope. Your feet push on the ground with a force like the brass pushes on the chamber. When the cosine of the angle is equal to the co efficient of friction between your feet and the ground, you start to slip. When someone pulls on you downhill, that force vector is summed with the force of your weight to make combined vector of force. When the cosine of the angle of the summed vector meeting the hill is equal to the co efficient of friction, the threshold of sliding is reached. Standing on a hill with an angle of .584 degrees or .477 degrees will make little difference. The force pulling one down hill is irrespective of the shape of the inside of the shoes, or the inside of the case. The maximum inside diameter of the case will give the same rearward thrust, be the inside tapered or straight with a square wall at the back. -- A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian. | |||
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Deke, The Clown is correct: you are expecting far, far too much from the AI case. Both QuickLoad and the Powley Computer predict your 2615 fps with a 150 gn bullet will be running at full .30-06 pressures, around 60,000 psi. As others have pointed out, the AI case gives you about 10% more powder volume below the bullet. At best, this will give you about a 5% increase in fps, or the 100 fps the Clown suggests. Why this is so can be seen with basic high school physics. Adding 10% more powder room lets you add about 10% more powder thus giving you the potential for about 10% more chemical energy to move the bullet. However, bullet energy increases with the square of the fps, and so a 5% increase in fps will be about a 10% increase in bullet energy, which is about all you'll get from that extra 10% more powder. The only way to increase fps beyond this is to increase the efficiency of the energy transfer from the powder to the bullet. Unfortunately, the biggest factor in determining this efficiency is the "expansion ratio," and this will decrease a bit when you increase the case size. The other way to increase it some is through higher pressure, and that is risky. Typically, however, a 10% increase in powder space will give you not a 5% increase in fps but only a 2 or 3 % increase. This is because you run up against the pressure limit with your old powder before you use up the extra space. If you're lucky, you can find another powder which will use up the extra space without running up the pressure, but don't count on this to give you that 5% alluded to before. If you want something unique, you might send your old 336 to McPherson or any other good Marlin gunsmith and have him change the stroke of the action to 2.73" or so, up from the 2.55" typ. for the 336. Your AI chamber got you 2, maybe 3 gn more case under the bullet, but seating the 170's for 2.73" COL will give you another 3 or 4 gn more. Now your cartridge won't look so sawn off, and you've increased the useable case nearly 20%. With this change plus a modest 5 to 10% increase in pressure, you might get 2500 with the 150's and 2325 with the 170's. The big limitation is pressure. SAAMI for the .30-30 is 42,000 psi (piezo), and that means you can't get much fps with a bullet of decent SD for hunting. The only way around this is a bigger case (say .30-40 size) and lots more slow powder to push the higher SD bullets. That's life. Enjoy it in good health. | |||
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Yes; The forward part of the case clings to the chamber wall. The part behind the pressure ring may stretch back if the pressure is high enough. The case stays forward until somthing like 40,000 psi. That is why a lower pressure cartridge with headspace will have protruding primers upon firing. If the case is lubricated it will come back at lower pressure. That is why oiling the case helps to fire form brass without stretching the"pressure ring". Finally, when the case head pushes back it exerts the same force on the breech oiled or not (the brass has gone into yeild). These things explain why Ackley could fire a Win 94 without the breech lock. Good luck! | |||
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asdf, Thanks for posting the high school physics lesson. I had all the pieces in my head already, and you connected the dots. One thing keeping the dots disconnected in my mind is that in load work ups, velocities seem to go up 10% with a 10% increase in powder. I know it doesn't make as much sense, but that is what happens. Quickload thinks that with a Speer 170 gr. flat nosed .308" bullet and 2.55" OAL, a 30-30 will have 2.152 cm^2 usable volume or 33.149 gr. H20. The 30-30 Ackley Improved, with the same bullet and OAL, will have 2.292 cm^2 or 35.321 gr. H20. The difference between 30-30 and 30-30AI in usable volume would then be 6.55% With a Speer 150 gr. flat nose bullet, the 30-30 and 37.370 gr. and the 30-30 AI has 39.543 gr. usable capacity. This is a 5.8% difference. Obviously, the larger the bullet the bigger the difference is usable volume. "Ackley vol. 1" 1962 shows: 30-30 150 gr 35 gr. 3031 2450 fps 30-30 AI as 38 gr. 3031 2700 fps. "Ackley Vol. 2" 1966 shows: 30-30 at 33.5 gr. 3031 2375 fps. When I ask Quickload to check those loads: 30-30, 35 gr. 3031, 51,197 psi, 2513 fps 30-30 AI, 38 gr. 3031, 60,013 psi, 2652 fps 30-30, 33.5 gr. 3031, 44,375 psi, 2408 fps When I ask Quickload for the SAAMI pressure of 42,000 psi with 20" barrel and 150 gr. Speer FN: 30-30, 32.9 gr. 3031, 41,920 psi, 2366 fps 30-30AI, 34.1 gr. 3031, 42,031 psi, 2395 fps I think the 59 fps gain [2.5%] for the Ackley improved version is more reasonable than the 250 fps gain [10.2%]. What does it all mean? A) The 30-30 Ackley Improved will improve the 30-30 velocity by 2.5% when both rifles are at 42,000 psi. B) The 30-30 Ackley Improved at 60 kpsi gets 13% improvement over a 30-30 at 42kpsi. -- A society that teaches evolution as fact will breed a generation of atheists that will destroy the society. It is Darwinian. | |||
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Deke, I think the 30-30AI will be a fun cartridge to play around with and that's more than half the fun. I hope you don't mind if I point out an observations from your last post: "to say that I should only get 2% fps gain with the AI is simply not even close to being true" I think asdf is saying that for a 10% gain in case capacity, you achieve a 2.5% gain in bullet velocity when both cartridges are loaded to equal pressure . IIRC, you were trying higher pressure loads with the 30-30AI. Between the case capacity increase and the pressure increase, you could see a significant gain (more than 2.5%) compared to the standard 30-30 at reduced pressure. However, if you loaded the standard 30-30 up to the same higher pressure level, you would get about 97.5% of the velocity obtained with the AI cartridge. The point I'm making is that yes, you are getting more than a 2.5% increase in bullet velocity compared to normal 30-30 loads but this gain came from two factors, increased capacity and increased pressure. Much of the velocity gain is due to the increased pressure. Of course none of this reflects on how much fun it is to play with and develop loads for the improved cartridge. I have a 260 AI and it is slightly better than the standard 260.......the difference is about 50 - 100 fps. Since I was chambering a new barrel, why not get all that would fit into the short action? HogWild | |||
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Clark, yes, there is a rule of thumb that a 10% increase in charge will increase fps by 10%. This comes, though, with an approx. 20% increase in pressure (as measured by CUP, more % if by piezo). As mentioned above, the increase in pressure increases the efficiency. As with most heat engines, increasing the pressure (and thus temperature) at which the energy is added (ie. powder burned) increases the efficiency of the conversion to mechanical energy (ie. bullet kinetic energy). With guns, another effect comes into play: increasing the charge (and thus pressure) can cause the powder to burn more completely; burning at low pressures can leave some of the powder unburned, which reduces efficiency even more. Off the top of my head, I do not have a simple explanation for this rule; it's been many years since I studied thermodynamics in college. If it comes back to me, I'll post again. Hodgdon and Lyman load books give CUP for max and starting loads, and this relationship can be seen there as well. The 2.5% increase in fps you found with QuickLoad is another published rule of thumb: that with a given psi limit and powder, increasing the useable case x % gives you an increase in fps of x/4 %. The writer Barsness has mentioned this one several times; and as you did, I found QuickLoad gives this same result. As I said, if you can find a powder with a slightly lower burning speed, you can get more powder in before hitting the pressure limit. Regarding your specific results from QuickLoad, I'll mention I haven't found QL particularly impressive at matching lab results when you ask it what happens when so many grains of such and such powder are put behind this bullet in that case. Indeed, I find 3031 to be one of the more poorly modeled powders in its database. The way QL mathematically represents the burning characteristics of powders contains several gross simplifications. As a result, certain powders end up with seemingly magical performance. Norma MRP is one magic powder in the version of QL I have. QL sometimes shows 3031 equaling 4350 even in largish cases with heavy bullets. Lastly, please note that my simple explanation given above did come with a caveat: to get the 5% more fps from the 10% more useable case assumes you are dealing with optimum powders, both before and after. Generally, best performance comes when you fill the case with a powder just slow enough that the psi limit is reached. If you increase the useable case volume by 10%, the optimum burning speed decreases slightly, and a matching powder may not exist. In your example you limited yourself to 3031 before and after the case was "improved." Try running QL again using only the VihtaVouri powders; their burning rates are fairly closely spaced. With a 45 gn .30-30 case and a 170 gn Sierra FP and a 24" bbl, QL predicts 2162 is the best fps w/o a compressed load, this with N140. Increase the case to 48 gn (an optimistic improvement), and the net case volume goes from 35.9 to 38.9 gn, a 8.4% gain. Now QL finds that N150 is the best powder, and fps rises to 2264, a 4.7% gain. This is closer to the 2:1 ratio I mentioned above. Again, this match with VV powders is just luck. In general, one won't find a perfect powder before and after. Further, QL's ability to accurately represent a given powder is limited, so this match up is even more lucky. Indeed, I'm not so sure it is ever practical to get the 2:1 increase in case:fps. The burning characteristics of smokeless powder may prevent a 5% gain with 10% more useable case; I just don't know. | |||
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Quote: Groan: I knew better than to use QuickLoad results to make a point. I grabbed my Lyman 48 and got some real world results. I compared the .358 to the .35 Whelen, and I compared the .308 to the .30-06 and the .300 Win. I find that rule of thumb about a 10% increase in useable case giving a 2.5% increase in fps is about right even when you do try to find the best burning speed. My simplistic explanation of why the Ackley will give only about a 5% increase in fps for its (optimistic) 10% increase in useable case is just too simplistic. I have a hunch as to why the ratio of fps increase to case increase is only 1:4 instead of 1:2, but my speculations have been wrong often enough of late  I'll just keep it to myself.In the end, the AI .30-30 case should offer no more than about a 2% increase in fps -- sorry Deke. | |||
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asdf, I agree with everything you said, but I have not given up on Quickload. Yes it has 3031 poorly characterized. It has R123 characterized worse. And QL also thinks my hot loaded straight wall cartridges [32acp, 380, 9mm, 9x23, 40sw, 10mm] handloads are over a million psi. But QL does give very good co relation with bottle necked cartridges [223, 308, 8mm, and 7.62x54] and my experiments with IMR4895 and H335. The velocity is very close match to my chrono, and the pressure predicted for my loads that make the extractor groove expand track the pressures, predicted by @$$Clown's Von Mises calculations, very well. Quickload reminds me of the Valhalla power meter of 20 years ago, you know it is working right when it gives the right answers. | |||
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Clark, What page of Ackley Vol II listed those reduced 3030AI loads? I have looked through both of my volumes (1962 and 1966) and could only find the loads in Vol I (1962). Deke. | |||
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asdf, I appreciate your efforts to estimate fps gains, but I have to say that my experience as well as others significantly contradicts your calculations. I will agree that as others have stated, the 38gr of 3031 w/Horn150RN's was too hot. However to say that I should only get 2% fps gain with the AI is simply not even close to being true. 37gr of 3031 (which an experienced 3030AI owner has suggested as max safe) produced 2559 (459fps/22% more than factory 3030). 35gr of 3031 produced 2450 (350fps/17% more than factory 3030). Finally, 33gr of 3031 (a full 5gr less than what was fired in my rifle) produced 2282fps (282fps/9% more than factory 3030). For those that are interested in the 3030AI ballistics that many others have found should go to an interesting thread @ http://www.marlinfirearms.com/ubb/Forum1/HTML/004467.html#6. I wonder if barrel length helps me more with the 3030AI than in its original 3030 chambering. I talked to Marlin about this and they confirmed that in their testing that 3030 velocities started slowing down with barrel lengths over 24" (kind of like a 22 rimfire starts slowing down with barrel lengths much over 16"......). What I am suggesting is that the 24" barrel optomizes the 3030AI chambering. Deke. | |||
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Deke, Vol II Page 408 and it is 30-30, not 30-30AI. | |||
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Clark, I most certainly have not given up on QuickLoad. I use it often, I recommend it to every reloader, I believe I have learned much about internal ballistics from it, and I am a much more cautious reloader after having learned from it. It is excellent for predicting performance potential and for learning about trends. Since I know many powders are poorly modeled in it, I choose to not use it to develop loads. HogWild, Yes, that is the point I was trying to make. Improving a case won't give you much fps. On the other hand, it does allow a fairly significant drop in pressure for the same fps, and that is good. In a given case, pressure rises at least twice as fast as fps. Given the problems in estimating pressure from fps, this allows for a better margin of safety, and in my mind, this is a good reason for using them. Deke, If Marlin told you they see muzzle fps from .30-30 cartridges actually fall off with barrels longer than 24", then I suggest you sell your Marlins and buy guns from a reputable maker. The expansion ratio of a .30-30 in a 24" barrel is under 13. Bullet fps begins to fall off at expansion ratios near 50, which is about what a .22 LR is in a 16" barrel. Some jacketed bullets may slow down before this expansion ratio, but not at 13. Muzzle pressure will be on the order of 5000 psi, which gives a shove on the bullet of about 375 lb. Think about this friend: what these A.I. users are telling you is they get .300 Sav performance in a case that's nearly 20% smaller under the seated bullet and rated at pressures about 10% lower. You don't have to trust my estimations nor the estimations of a computer program such as QuickLoad. Go pick up a good load book and try to find a single example where a smaller case delivers more performance at lower pressure. THIS DOES NOT HAPPEN. There is certainly no need to trust my estimations, for you can find these trends yourself in load books such as Lyman 48 and Hodgdon 2004. Watch how pressure rises from min. to max. loads: compare the % increase in charge to the % increase in fps and pressure. Compare cartridges of the same bore and pressure and observe the change in max. fps with a change in internal case volume. The approximation that fps gain = 1/4 the gain in case volume is there for anyone who'll crunch a few numbers to find. Your rifle is a 1948. There have been great strides in metallurgy since then; the quality is more uniform today. Further, modern Marlins are made of steel selected to take hot loads in fat .45-70 cases. It is not prudent to assume your 1948 was as well. Enough said. While you probably won't end up looking like a unicorn, albeit with a Marlin bolt in place of a horn, I see no need to risk it. | |||
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Clark, Thanks for the clarification. I did not see that you had quoted 3030 in Vol II. asdf, Despite what Marlin told me, I'm not going to sell the Marlins and I doubt anyone else will either. Infering that they are not a reputable gun maker due to what one of their technicians told me is a stretch. I appreciate your candid input and technical explanation. Now back to the original intent of this post. Some recomend strain gauges, but they won't fit on my gun. Others recomend PRE while as many others seriously doubt it. Is there a reliable method of detecting excessive pressure in a relatively low pressure cartridge that most of us can agree to? Deke. | |||
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Deke, I have never read of any way a handloader can gauge pressure short of using the strain gauge. Since this is not an option for you, the best you can do is infer pressure from fps, which is what I've been trying to do. I realize this way is not exact. It depends on general trends observed across many different cartridges. As I mentioned, it is rare that a given cartridge will have a perfect match to some powder. I'm sure it does happen, but without a piezo or strain gauge, we can't find it. You seem to want 2550 fps from your gun. I picked up Hodgdon's from my book shelf and see they claim nearly 2400 fps for the 150's and a 24" barrel with H4895. This suggests 2450 for the A.I. at the same pressure. Extrapolating another 100 fps is 10-15% more pressure. At least this isn't in the proof load range. On the other hand, lab data is not infallible. Sadly, Lyman didn't check H4895 in their most recent tests, but they suggest 335 will do nearly as well. On the other hand, Hodgdon max'ed out with 335 at nearly 100 fps lower. As you can see, trying to run at the extremes of fps is iffy. I long ago gave up trying to do so. I no longer even consider top load book fps unless I can find data from at least 3 labs in agreement, and that is RARE. I'm not aware of the history of the 336. Was there a hotter cartridge loaded for it circa 1948? I thought it was pretty much .30-30 and .35 Rem. Then again, maybe the steel they happened to use was enough stronger than necessary to allow a steady diet of proof loads. Maybe... Karl the (overly?) Cautious, signing off | |||
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Deke... Unfortunately, the short answer to your question is no. The two next best procedures that I can think of are QuickLoad, and inferring from muzzle velocity. The Marlin is a bit stronger than other guns. You may get some improvement through that, too. | |||
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ASSCLOWN, Hope your road trip went well. Spoke to my smith and he gave me 12 square threads per inch, OD=.780", length could vary from .771"-.885" (he could not remember what mine was). However, he said that unless you know the properties of the steel in my gun, hoop strength calculations would not be accurate. With this being the case I assume that you are trying to determine a range of strength that my barrel shank will fall within. Your recomendation of a .0015" PRE is somthing I will seriously consider. I will also use brass from the factory ammo that I got my base PR measurements from to minimize variations due to diff lots of brass and fired only once or twice so work hardness does not become an issue. Along with the 37gr of 3031 and Hornady 150gr bullet, could you (or anyone else with Quickload) calc required powder charge of Varget and H4895 for a 2500fps mv with Barnes 150XFN in the 3030AI and what the resulting pressure would be (if you are too busy I understand) so I can cross reference with manuals and do more head scratching? BTW, my smith and another 3030AI/336 owner really thought I would see sticky extraction in a lever action before I ever got into trouble. I never had any stickiness and I was paying close attention. My smith also noted that folks are building 50Alaskans on the 336 action so it is strong. He also said that he once did 30 rifles all the same make/model rifle for one client, all the same cartridge, and there was 300fps difference from the slowest to the fastest, driving home the point that each is a beast unto its own. Finally, to set aside concern that I may rush into somthing and damage my rifle and/or me, I am not in a hurry and will be thorough and safe. This is unchartered water and not much published data is available on the 3030AI. I want to be safe while not skimping too much on the potential of this rifle. Thanks again for everyone's help. Deke. | |||
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Deke, Regarding your QuickLoad request, I used the XFN seated for a COL of 2.55" and used a case capacity of 48.9 gn (from your earlier post). For Varget, it suggests 35.7 gn (which will roughly fill the case) producing a nominal pressure of 50 ksi. For H4895, 35.5 gn (again about a full case) at 54 ksi. Please be aware the author of QL tells you in no uncertain terms to design for a pressure 7/8 of the desired maximum. I believe this is to allow for the typical variation in pressure found from one round to the next. In other words, if the nominal Varget load runs 50 ksi, you must expect pressures to range up to 8/7 of that or 57 ksi; and for the 54 ksi H4895, expect pressures in some rounds to run upwards of 62 ksi. Please be aware that your rifle might have been proofed with only 55 - 59 ksi. In other words, some of your rounds may exceed proof with either powder. I should note I find that QL's estimate of charge is often below that found in data books. In other words, you may need to use compressed loads to get your 2500 fps. QL suggests 335 and BL-C2 will offer you somewhat lower pressures (2 ksi) and leave a bit more powder room free to work with. Regarding your gunsmith's comments on the strength of the 336 action, yes, your old 1948 might have the same cross sections, but does it have the same steel as the modern jobs? One other idea: if you want to test the safety of your hot new load, you could proof your gun for your new "normal" level. The minimum proof load by US, UK, and Continental standards is 130% of normal max. Judging both by QL results and by extrapolation of published lab data, I think a 10% overcharge would do as your proof load. That is, when you settle on your "max safe" load, you then want to light off a single cartridge charged with 10% more of the same powder. I also recommend a very long string connecting you to the trigger. I also recommend an empty firing range when you light this baby off. You're aiming for about 78 ksi in that skinny barrel. The problem with proofing your gun yourself is determining if any plastic deformation has occured. The factories probably have special jigs for measuring the before and after dimensions of all the critical spots. One possibility for you would be to average several chamber casts before and after proofing. That would let you know if the barrel and receiver ring have given. You would also have to establish that headspace changed not at all. The only way I can think to do this is to first turn from brass a case body with a rim thickness a bit over max. Then carefully sand off the base .0001" at a time until the action locks with great difficulty. After firing the proof load, if the action locks more easily on this headspace gauge, the gun has failed proof and should be destroyed. Best wishes, Karl | |||
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Quote: I'm not sure about DETECTING, but what happened to the Powley Computers?  I once had a set of these (probably still, do, somewhere!!). They were cardboard slide rules, one of which permitted you to calculate a powder charge for IMR powders based on case capacity and bullet sectional density, etc. The result was a safe starting load and a predicted MV. There was a pressure calculator slide rule along with the powder charge calculator that allowed you to calculate the likely pressure of a given load based on powder type, MV, case capacity, bullet SD, etc (I'm going from memory, and some of the factors may have been different from what I've listed). But at the time these tools were being touted, it was generally agreed that the results they produced were useable, and gave safe information.I don't know if anyone still sells these things, if they have been superceded or discredited, or what? Hey! I just found the Powley computers online! You can find them at: http://users.bwsys.net/~kwk/powley.html There is some kind of a pressure predictor calculator at that site. Might be worth a try! | ||
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Quote: Oooo, I'm discovered. That is a version I wrote a year ago. I've had a change of heart on the usefulness of the pressure computer. It does indeed seem to predict trends in pressure and fps, but it does NOT correctly account for pressure and fps variations that can occur due to primers and bullet construction. Some details are given in the old version. I've collected a little more evidence since then. I have an updated version of this Powley Computer on my PC, but I'm awaiting Ken Howell's new book on internal ballistics before making a final version. On other forums, Howell has indicated the original computer had some minor errors regarding the design pressure of the load computer. Since Howell was a friend of Powley and says he has Powley's old notes, I want to wait for his insights. I also need to add a few more instructions regarding how to use my HTML version. Please note the calculations are based on the version published by William Davis in the NRA reloading book. I recently acquired a slide rule version, and the equations from Davis do not always pick the same powder (the charge calculations give the same results; the pressure computer seems to be correct, but I need to play with it further). For what its worth, the slide rule seems much more likely to pick an inappropriate powder. Just looking at the scales on the slide rule, one can see it is not the same equation that Davis provides, and Davis said he got his from Powley. I hope to learn more from Howell's book. Karl | |||
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