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Masking high chamber pressure symptoms

NCHillbilly

Libertata Aut Morte
Full Member
Minuteman
  • Jul 7, 2012
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    The occupied states of America
    I have been handloading for quite a while, but only recently have I been really pushing my loads to the max. In the past, I'd open the load manual, begin with the starting charge, and stop at the first accurate load that I found. Now, I'm working up as far as I can go until I start seeing high pressure signs. My question is this; If I'm working up a load, and start seeing pressure before I reach some pre-determined velocity, And I replace a buffer( gas gun) to eliminate ejector swipes, is this not creating a potentially dangerous situation? The presence of ejector swipe is letting me know that high pressure exists, so by eliminating the swipe, high pressure still exists, but now I may try to go even farther, without knowing the absolute max till it's too late. I want all the velocity I can get, just don't want to destroy a weapon or my face.
     
    A ejector swipe in a AR isn't necessarily indicative of excessive chamber pressure.
     
    A ejector swipe in a AR isn't necessarily indicative of excessive chamber pressure.
    I was always led to believe flattened primers and ejector swipes were the signs to look for when pressure started to build. I have some loads that will start to flatten primers WAY early, and I've learned to ignore them by themselves.
     
    What, exactly, should I be looking for as far as pressure signs? I know some of the load manuals are very conservative with their listed charges. If you ease past book max looking for accuracy or velocity, how will you know when it's getting close to being too much? I am talking about gas guns. I work up loads that I find on here, that are working for others, and a lot of them are above posted book max charges. Even some That I've worked up from the manuals end up above book max, not by a bunch, but they are above. I'm just trying to stay safe while getting all I can.
     
    What, exactly, should I be looking for as far as pressure signs? I know some of the load manuals are very conservative with their listed charges. If you ease past book max looking for accuracy or velocity, how will you know when it's getting close to being too much? I am talking about gas guns. I work up loads that I find on here, that are working for others, and a lot of them are above posted book max charges. Even some That I've worked up from the manuals end up above book max, not by a bunch, but they are above. I'm just trying to stay safe while getting all I can.

    Why do you want to load above book recommendations? What are you trying to gain? Unless you have the greatest load in the world all you're going to do it spend more money than you have to.
     
    Why do you want to load above book recommendations? What are you trying to gain? Unless you have the greatest load in the world all you're going to do it spend more money than you have to.
    Like I stated earlier, I want all I can get, as long as it's safe. The difference between an accurate load at 2400 fps vs 2800 fps means quite a bit regarding trajectory. I am not willing to destroy my rifle for that last 50 fps, which is where the original question came from. Many guys in the loading threads post loads with velocities, and I know a lot are above book max due to the fact I've loaded to book max and am still fps below them. I know to consider barrel length, twist rate, action type, temperature, all that stuff. It's easy with a bolt gun, just wondered if there was a quick and dirty way to tell with gas guns, since that is what I play with the most. I have considered quickload software, which I'll probably end up getting. Handloading and load development is my hobby, I'd like to advance my knowledge to get the full potential from my loads.
     
    Excessive case growth
    To the point, the latest loads I've worked on have given me the best accuracy at .6grs above book max. My brass has not grown enough to cause concern, and the primer pockets are still good. According to fellas that have worked with this cartridge for a while, there should be a node above where I'm at, but I'm already above (barely) book max.
     
    Are you using the same components as the book? Max in one case is a medium load in another.
     
    Like I stated earlier, I want all I can get, as long as it's safe. The difference between an accurate load at 2400 fps vs 2800 fps means quite a bit regarding trajectory. I am not willing to destroy my rifle for that last 50 fps, which is where the original question came from. Many guys in the loading threads post loads with velocities, and I know a lot are above book max due to the fact I've loaded to book max and am still fps below them. I know to consider barrel length, twist rate, action type, temperature, all that stuff. It's easy with a bolt gun, just wondered if there was a quick and dirty way to tell with gas guns, since that is what I play with the most. I have considered quickload software, which I'll probably end up getting. Handloading and load development is my hobby, I'd like to advance my knowledge to get the full potential from my loads.

    The difference between a safe load and over book max isn't 400fps. Find what the gun likes with the components you have other wise change the components or gun. Tons of load data gets posted here that is questionable at best.
     
    The difference between a safe load and over book max isn't 400fps. Find what the gun likes with the components you have other wise change the components or gun. Tons of load data gets posted here that is questionable at best.

    He mentioned he used to always pick the FIRST accurate node, which would mean he used to load closer to the starting load than max. If he's now loading over max, there very well could be close to 400fps difference there. I've found an accurate node at around 2500fps in my AR, which is over starting charge...and then ramped up that same setup to NATO max which yielded 2830-2850fps... so definitely doable.

    If you think going over book max is stupid, thats fine, then stay within the limits yourself. He asked for advice, not a lecture from papa


    OP, it's definitely tougher to figure out pressure signs in a gas gun over a bolt gun. Some of it is going to come down to knowing your rifle as well. Inspect brass on near max, but obviously safe loads, and continue to inspect as you increase charges. My AR puts a minor ejector swipe on most charges over halfway...but when I got to the top of the NATO charges for TAC, you could see harder indentation, and the swipe itself was wider and more pronounced.

    Pay attention to gas as well. I keep my adjustable gas block on the same setting for all load development, as I shoot suppressed for everything. Example: with TAC and 77TMK's, anything over ~24.5gr was noticeably more gas and the ejector marks were more pronounced. So it wasn't the simple existence of a traditional pressure sign, it was the change to an increased evidence of said pressure signs.

    Just work slow and pay attention to all the details.
     
    He mentioned he used to always pick the FIRST accurate node, which would mean he used to load closer to the starting load than max. If he's now loading over max, there very well could be close to 400fps difference there. I've found an accurate node at around 2500fps in my AR, which is over starting charge...and then ramped up that same setup to NATO max which yielded 2830-2850fps... so definitely doable.

    If you think going over book max is stupid, thats fine, then stay within the limits yourself. He asked for advice, not a lecture from papa


    OP, it's definitely tougher to figure out pressure signs in a gas gun over a bolt gun. Some of it is going to come down to knowing your rifle as well. Inspect brass on near max, but obviously safe loads, and continue to inspect as you increase charges. My AR puts a minor ejector swipe on most charges over halfway...but when I got to the top of the NATO charges for TAC, you could see harder indentation, and the swipe itself was wider and more pronounced.

    Pay attention to gas as well. I keep my adjustable gas block on the same setting for all load development, as I shoot suppressed for everything. Example: with TAC and 77TMK's, anything over ~24.5gr was noticeably more gas and the ejector marks were more pronounced. So it wasn't the simple existence of a traditional pressure sign, it was the change to an increased evidence of said pressure signs.

    Just work slow and pay attention to all the details.
    I inspect EVERY piece of brass, and work up slowly. Just trying to learn.
     
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    He mentioned he used to always pick the FIRST accurate node, which would mean he used to load closer to the starting load than max. If he's now loading over max, there very well could be close to 400fps difference there. I've found an accurate node at around 2500fps in my AR, which is over starting charge...and then ramped up that same setup to NATO max which yielded 2830-2850fps... so definitely doable.

    If you think going over book max is stupid, thats fine, then stay within the limits yourself. He asked for advice, not a lecture from papa


    OP, it's definitely tougher to figure out pressure signs in a gas gun over a bolt gun. Some of it is going to come down to knowing your rifle as well. Inspect brass on near max, but obviously safe loads, and continue to inspect as you increase charges. My AR puts a minor ejector swipe on most charges over halfway...but when I got to the top of the NATO charges for TAC, you could see harder indentation, and the swipe itself was wider and more pronounced.

    Pay attention to gas as well. I keep my adjustable gas block on the same setting for all load development, as I shoot suppressed for everything. Example: with TAC and 77TMK's, anything over ~24.5gr was noticeably more gas and the ejector marks were more pronounced. So it wasn't the simple existence of a traditional pressure sign, it was the change to an increased evidence of said pressure signs.

    Just work slow and pay attention to all the details.

    Is this where the goal posts and original intent of the thread shifts because the OP and you don't like the answer? NATO spec 5.56 ammunition has a called out specification, it isn't what is considered over maximum pressure for 223 Remington in the manual. Max pressure for 5.56 is generally 62K PSI but varies depending on the cartridge in question. Many manual have a separate section for 5.56 and 223 Remington. 5.56 is not generally considered 223 Remington with regards to reloading manuals or even QL. If OP had asked about MK262 specs, for example, he would have been given the information pertinent to the question. Instead he asked about safety as it pertains to disregarding pressure signs. There may vary well be a 400fps difference between the minimum safe starting charge weight from a reloading manual and the NATO specified velocity for certain cartridges but that isn't what was asked nor what was answered.

    The correct answer is once you see pressure signs back down. It is generally at the front of every manual. Ejector swipes aren't necessarily pressure signs. If you've been hand loading for a while this would be fairly obvious. Over max loads (showing pressure, breaking parts, prematurely wearing out barrels, etc) are rarely worth cost, regardless of the minimal performance gain.
     
    Whoa there, where did I say I didn't like your answer? I do get the impression you think I may be wrong in what I'm trying to do, but I'm not 100% sure that I've done a very good job explaining exactly what it is that I'm trying to do.
    For starters, I'm not specifically talking about 5.56 nato, although the cartridge really doesn't matter. Same principles regardless. I'll try again to lay this out. To begin with, I (erroneously) thought ejector swipes were a pressure sign to watch for, which I do. I have also read that if you are getting swipes, but are below a certain known node/velocity, that a heavier buffer would eliminate said swipes. Because I THOUGHT swipes were a sure-fire way to gauge high pressure, it seemed to me that use of a heavier buffer was just covering up the symptom. Kinda like an athlete getting injured, getting a shot to kill the pain, going back in the game and getting severely injured because the pain was gone.
    I'm not trying to formulate the greatest load of all time for anything, I'm trying to get the most I can out of a given load and do it safely. The same reason that a racer with 500 horsepower wants 600. If I know what to look for and how to read the pressure signs, I can safely maximize my loads. If you don't think I should go over book max, you're entitled to that belief. No goalposts have been moved, nothing has changed from my original post, except A few fellas have given me some useful information, and some things to consider. I appreciate all the responses, including yours. I never intended this thread to turn into a pissing match, just wanted some clarification and to try to learn a little more. If I know someone shooting the same cartridge out of the same length barrel with the same twist rate is shooting .7 moa at 150 fps more than I am out of a similar action rifle, then yeah, I feel like I could ease my way up to it. But I want to be checking the necessary things on my way up. If I can't get there, then fine, but I'm not gonna stop trying just because a lawyered-down load table says I'm at max, but I have no pressure signs. Do you get where I'm coming from? I don't expect to shoot an 80gr out of a 224 valk at 3000 fps, but I'm not gonna stop at 2500 just because I found a node, and it's below book max. I feel like I'm leaving something on the table
     
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    And for the record, I've never broken any parts, never blew out the gas rings, split cases, or lost a primer, so I'm relatively certain my loads have not been TOO hot up till now.
     
    As a general rule, when I develop gas gun loads, I take the gas system out of the mix and shut off adjustable GBs or loosen gas plugs so I can tell if it's really pressure and not the bolt unlocking early.
    Hard extract and excessive case stretch are the two things that make the alarm bells go off for me.
    FWIW, I do consult a few sources for what "max" really is. Lyman is super conservative, most of my loads are a tick above their published max. I'm usually a touch under Hodgdon and Sierra max. Berger's data is a bit hot for my comfort level.
     
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    I usually include hodgdon max in tests with thier powder and have not popped anything yet.

    Odd that about 1/2 a grain under is close to my best results for most combinations.

    I keep wanting to go faster and my groups keep telling me no.

    Is what it is I suppose.
     
    Is this where the goal posts and original intent of the thread shifts because the OP and you don't like the answer? NATO spec 5.56 ammunition has a called out specification, it isn't what is considered over maximum pressure for 223 Remington in the manual. Max pressure for 5.56 is generally 62K PSI but varies depending on the cartridge in question. Many manual have a separate section for 5.56 and 223 Remington. 5.56 is not generally considered 223 Remington with regards to reloading manuals or even QL. If OP had asked about MK262 specs, for example, he would have been given the information pertinent to the question. Instead he asked about safety as it pertains to disregarding pressure signs. There may vary well be a 400fps difference between the minimum safe starting charge weight from a reloading manual and the NATO specified velocity for certain cartridges but that isn't what was asked nor what was answered.

    The correct answer is once you see pressure signs back down. It is generally at the front of every manual. Ejector swipes aren't necessarily pressure signs. If you've been hand loading for a while this would be fairly obvious. Over max loads (showing pressure, breaking parts, prematurely wearing out barrels, etc) are rarely worth cost, regardless of the minimal performance gain.

    I agree with everything you said here... maybe I should have used a better example. Another example would be Hodgdon's listed loads for 147's and H4350. Their max is as 41.8gr, which ended up being my actual load and does great, and have shot it up to 90* so far without problems. I have though, gone up to 43gr, seeing pressure increase at 42.8. I have also loaded 42.2gr with about the same success as 41.8. In my rifle 41.7-42.2 seems to be a relative "node" if you will.

    I think the point is... Over book max isn't always actually over max, as the OP was talking about book max, not an obvious pressure signed max from his specific rifle. I agree pushing loads too far isn't conducive to keeping your rifle in good working order, but going over a book max is also not necessarily bad provided you're watching for the signs, which is really what this whole post is about.

    I hope we're back on track. OP, I think your line of thinking is fine, and I think trying a different buffer could help work out the swipe issue. If it does, I agree with @Cascade Hemi that its probably not a pressure issue, but a heavy ejector or a gas timing issue.

    My factory Savage creates a small primer crater with every load from start to end, as the bolt/firing pin combo is prolly a little loose and makes this happen. Savage tends to have some less manicured edges/parts from the factory and my Ejector creates small marks on all of my brass. When I hit real pressure, those marks become more pronounced and heavier, and thats usually when I note that charge and back off 1-2%.
     
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    I think Bolo has a good idea too.
    turning off the gas to eliminate that during load development.

    on another note, take IMR 8208 XBR. the book max depending on which book is anywhere from 22.7 to 23.1 with a 77gr sierra for 223.
    I would venture to say 95% of the guys out there load that popular combo above book max, often ending at 23.6, a full half grain over the highest published book max.
    book max is a yellow light for most reloaders for most combos, not a hard stop red light, depending on caliber, combo, etc.

    a guy has to figure out that for himself, be cautious and safe along the way.
    seems like the OP is doing just that.
     
    I agree with everything you said here... maybe I should have used a better example. Another example would be Hodgdon's listed loads for 147's and H4350. Their max is as 41.8gr, which ended up being my actual load and does great, and have shot it up to 90* so far without problems. I have though, gone up to 43gr, seeing pressure increase at 42.8. I have also loaded 42.2gr with about the same success as 41.8. In my rifle 41.7-42.2 seems to be a relative "node" if you will.

    I think the point is... Over book max isn't always actually over max, as the OP was talking about book max, not an obvious pressure signed max from his specific rifle. I agree pushing loads too far isn't conducive to keeping your rifle in good working order, but going over a book max is also not necessarily bad provided you're watching for the signs, which is really what this whole post is about.

    I hope we're back on track. OP, I think your line of thinking is fine, and I think trying a different buffer could help work out the swipe issue. If it does, I agree with @Cascade Hemi that its probably not a pressure issue, but a heavy ejector or a gas timing issue.

    My factory Savage creates a small primer crater with every load from start to end, as the bolt/firing pin combo is prolly a little loose and makes this happen. Savage tends to have some less manicured edges/parts from the factory and my Ejector creates small marks on all of my brass. When I hit real pressure, those marks become more pronounced and heavier, and thats usually when I note that charge and back off 1-2%.
    YES, YES, YES. You get exactly what I'm trying to do. Just going after all I can get, SAFELY, nothing more.
     
    I have been handloading for quite a while, but only recently have I been really pushing my loads to the max ... I want all the velocity I can get, just don't want to destroy a weapon or my face.
    You asked, I have an opinion.

    There are several signs for pressure. One classic pressure sign is "primer metal cratering around the firing pin". Some are more reliable than others. For example, I shoot Federal primers, they are notoriously "soft". I get primer cratering with moderate loads and no other pressure signs - it's a red herring. If I make a load using Federal match primers and they show cratering, I don't worry unless I also have another sign. I have owned weapons where the firing pin hole in the bolt face was a bit large. That will always crater Federal primers without other pressure signs and may crater harder primers.

    I own a brand new box of federal gold medal match 223 brass. In my weapons, with my standard loads, case heads expand after one shot. Please don't misunderstand, I am not picking on Federal - I use their primers for all precision work and I am happy with their products and I recommend them but I don't shoot that brass in my gas guns and I know to ignore cratered primers.

    In some guns pressure signs show up all at once, in other guns they show up in a sequence - first sign 1, then signs 1 and 2, and so forth. If I see one reliable sign, I see yellow lights and I pay close attention. If I see two or more signs, red lights start blinking. When I see difficult to extract and case bases expand, I know that something bad just happened. If the bolt won't close on a piece of brass I just fired, something bad just happened. If the primer pockets won't hold a primer then I was a bad boy. Here is my list:
    • difficult to extract, for an unfired round, can also be bullet seated too long
    • case head expansion, measure the rim and and just above the extractor groove.
    • Case separations, head or body, can also be caused by bumping the shoulders back too far.
    • cratered primers, check primer brand and firing pin hole in bolt face
    • Primers smashed flat, can be caused by soft primers and (maybe) by making the flash hole too large.
    • pierced primers, can also be caused by not seating deep enough and firing pin protruding too far and
    • Case head ejector hole marks might be (a) too much pressure for this brass, (b) burrs around the ejector hole (c) you annealed the case head. Never anneal the case head. I have been told that some people get ejector marks if their brass is too short or too long. I haven't seen it but there you go. Try different/harder brass.
    • "no-go" gauges that "go"
    • unexpected rapid disassembly - sort of the ultimate sign.
    I once accidently made a batch of 300 win mag using heavy bullets and 10 grains too much H1000 powder. There was much noise, flash, and recoil. The excess gas from my brake blew stuff off my shooting bench. I had to hammer the bolt open. The case was wrecked but the gun was fine. It didn't have to turn out fine.

    Does accuracy matter to you? As you push the pressure, how does the gun group? With very few exceptions, very hot loads don't group as well.

    Does case life matter to you? If you have an unlimited supply of brass, you may not care about brass life so long as the case is intact enough to eject. Otherwise, as you are testing, you might keep using the same few pieces of brass and see how long they last.

    Does barrel life matter to you? The velocities that go along with relatively high pressure erode the throat. Guns with eroded throats shot bigger groups. If it didn't matter, benchrest shooters would not swap barrels every 1,000 rounds.

    I saw two guys blow up their guns - this is yer basic "unexpected rapid disassembly". Both were a messy. And the guns were wrecked too. The first guy was scalped and the second guy looked like he had been used as a 40 yard shotgun patterning target. If you are going to run very high pressure, you might want to buy a no-go gauge and check your weapon as you test. Chances are you will see other signs first but when you get above 70,000 PSI things start to happen pretty fast.
     
    You asked, I have an opinion.

    There are several signs for pressure. One classic pressure sign is "primer metal cratering around the firing pin". Some are more reliable than others. For example, I shoot Federal primers, they are notoriously "soft". I get primer cratering with moderate loads and no other pressure signs - it's a red herring. If I make a load using Federal match primers and they show cratering, I don't worry unless I also have another sign. I have owned weapons where the firing pin hole in the bolt face was a bit large. That will always crater Federal primers without other pressure signs and may crater harder primers.

    I own a brand new box of federal gold medal match 223 brass. In my weapons, with my standard loads, case heads expand after one shot. Please don't misunderstand, I am not picking on Federal - I use their primers for all precision work and I am happy with their products and I recommend them but I don't shoot that brass in my gas guns and I know to ignore cratered primers.

    In some guns pressure signs show up all at once, in other guns they show up in a sequence - first sign 1, then signs 1 and 2, and so forth. If I see one reliable sign, I see yellow lights and I pay close attention. If I see two or more signs, red lights start blinking. When I see difficult to extract and case bases expand, I know that something bad just happened. If the bolt won't close on a piece of brass I just fired, something bad just happened. If the primer pockets won't hold a primer then I was a bad boy. Here is my list:
    • difficult to extract, for an unfired round, can also be bullet seated too long
    • case head expansion, measure the rim and and just above the extractor groove.
    • Case separations, head or body, can also be caused by bumping the shoulders back too far.
    • cratered primers, check primer brand and firing pin hole in bolt face
    • Primers smashed flat, can be caused by soft primers and (maybe) by making the flash hole too large.
    • pierced primers, can also be caused by not seating deep enough and firing pin protruding too far and
    • Case head ejector hole marks might be (a) too much pressure for this brass, (b) burrs around the ejector hole (c) you annealed the case head. Never anneal the case head. I have been told that some people get ejector marks if their brass is too short or too long. I haven't seen it but there you go. Try different/harder brass.
    • "no-go" gauges that "go"
    • unexpected rapid disassembly - sort of the ultimate sign.
    I once accidently made a batch of 300 win mag using heavy bullets and 10 grains too much H1000 powder. There was much noise, flash, and recoil. The excess gas from my brake blew stuff off my shooting bench. I had to hammer the bolt open. The case was wrecked but the gun was fine. It didn't have to turn out fine.

    Does accuracy matter to you? As you push the pressure, how does the gun group? With very few exceptions, very hot loads don't group as well.

    Does case life matter to you? If you have an unlimited supply of brass, you may not care about brass life so long as the case is intact enough to eject. Otherwise, as you are testing, you might keep using the same few pieces of brass and see how long they last.

    Does barrel life matter to you? The velocities that go along with relatively high pressure erode the throat. Guns with eroded throats shot bigger groups. If it didn't matter, benchrest shooters would not swap barrels every 1,000 rounds.

    I saw two guys blow up their guns - this is yer basic "unexpected rapid disassembly". Both were a messy. And the guns were wrecked too. The first guy was scalped and the second guy looked like he had been used as a 40 yard shotgun patterning target. If you are going to run very high pressure, you might want to buy a no-go gauge and check your weapon as you test. Chances are you will see other signs first but when you get above 70,000 PSI things start to happen pretty fast.
    Thank you for the reply. I'll answer your questions, and give a little more info on what I'm currently working on.

    At the moment, I'm working up loads for a .224 valkyrie, used in an ar platform. Accuracy very much matters to me. I am seeking to load the most accurate round with as high a velocity as possible, all while being SAFE. I have found a very accurate 80gr load, that is .3-.6grs above BOOK max. I have no signs of high pressure at that charge weight. Many guys that have worked with this round much more extensively than I have found another node higher than where I'm at now. If I can get acceptable accuracy at a higher velocity without destroying my rifle, my brass, or myself, I would choose to do that. If not, then I've got what I've got and I will live with it.
    I have used cci primers almost exclusively since I began loading many years ago, and found I would start to see slight flattening relatively early in the load development. No cratering, no pockets blown out, no other signs of pressure, so by itself, I don't worry too much about that. I was just curious if there was something else I could use to identify mounting pressure while at the range, as I pick up and inspect the cases each time I fire a batch of like-charged cases. I don't carry calipers or micrometers to the range, just a chronograph and detailed info on the loads. I shoot for groups, measure the velocity, inspect cases (to the best of my ability), mark up targets, put cases back in the ammo boxes where they came from and go home. Once home, I can get out the measuring tools, check cases, measure groups, calculate sd and es, and move on.
    The range where I shoot is an hour away, so all I can do is load a batch and go shoot. I don't have the luxury of loading 5 rds, step outside, shoot, come back in and load 5 more (I wish I did), but I think from the responses I've gotten in this thread, pretty much tells me there's really not a good way to visually tell when pressure is getting too high without actually measuring the cases, unless, of course, they are loaded WAY too hot. Like I said earlier, I have no intention of destroying my rifle to squeeze that last 50 fps out of it, but I want all I can get, SAFELY. I know this will sound crazy to some, but I still load on a single stage, and I hand weigh every charge. I am very safety conscious, which is the whole point of this thread. Every ounce of info I can glean from others just helps me be more successful. Thanks again for your input.
     
    Load data is often conservative but also specific to the firearm used. Keep an eye on the velocities your chrono measures because they can also be an indicator of pressure even when your brass looks fine. Otherwise, I don't see anything wrong with your methodology.
     
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