Quick load vs pressure signs

Discussion in 'Reloading' started by snox801, Nov 5, 2018.

  1. snox801

    snox801 Well-Known Member

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    Ok so I’ve always been curios of this. Which do most go by? I’ve always wanted to see where mine shows pressure and go that route. But sometimes quickload says it’s hot before that happens. Plus I see people saying you can push lapua brass harder but again that show to be high in quickload.
    So my 6.5 creed shooting the hammer 124gr with varget and lapua brass show no sign of pressure on the primer or brass. Bolt lift is a bit tough to tell as it’s a pierce ti and is very tight to start with after bolt was coated. This part is slowly getting better the more I shoot. So question is should I go till I see the brass show then back off or go by quickload that says I’m hot. Seems kirby and other go by brass as I got more speed out of the new brass he uses before it showed pressure. Also the bullet design and freebore may throw off quickload right?
     
  2. Rhovee

    Rhovee Well-Known Member

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    Quickload is a computer program that gives approximate psi. If you take a 30/28 Nosler for example, it said I should of pressured out around 3000 FPS. Well I run at 3115 and pressure was 3150. Don’t get me wrong. It’s a hot load. 3-4 firings on Nosler brass. I would go off what your rifle says. For my 7 saum is showed 2930 FPS to be 65k pressure which is max. I have ran 2920 for accuracy and primer pockets are still very tight on 7 firings. I seriously doubt that it’s 65k psi with that many reloads.
     
  3. Engineering101

    Engineering101 Well-Known Member

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    I've used Quick Load for years. It is a great program and has many uses. Getting accurate pressure info is NOT one of the uses.
     
    MajorSpittle and B23 like this.
  4. phorwath

    phorwath Well-Known Member

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    MV us a great way to ID pressure. When your MV is matching velocity in the reloading manuals, then you're going to be in the ballpark of those listed pressures, as compensated for different barrel lengths and bullet construction.

    It's not perfect apples to apples comparison. Better than Quick Load predictions though.

    If you want maximum MV, you'll go by what your brass can withstand. The brass case head should always fail first as pressure progressively increases. Pressure can be observed and even measured on the case head and case web. Not all cases are created of equal case head strength. So if you desire maximum MV with your cartridge cases, you'll have to monitor pressure off your fired casings.
     
  5. snox801

    snox801 Well-Known Member

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    Thanks guys that’s what I thought but always better to double check with people better than me at this.
     
  6. Mikecr

    Mikecr Well-Known Member

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    This is often correlation without causation.
    That is, 'Problems' occurring with increasing pressure may be pressure problems -but not problem pressures.
    A really good example of this is with primer pockets loosening. By far most believe this is a symptom of problem pressures, and it can be. But it can also present with moderate pressure shooting of rat turds in a violin case.
    Some folks can remove a problem assumed as pressure with bushing of their bolt for reduced firing pin clearance, or better control over their headspacing. They'll crack fewer cases with better matching of their sized cases to individual chamber. Many bolts are mistimed and extract with problem difficulty.

    There is a way to test for and monitor 'local Max Pressure' as it manifests into problems for sizing & extraction. I call it 'MyMax', and it has nothing to do with published, predicted, or actual pressure. It is simply the point of case expansion where body sizing is required to rechamber the case. I measure it with a blade mic, ~.2-.25" up from the extraction groove, at a visual web-line. I do a new brass test, increasing incrementally in charge and plotting the web-line result. It will grow, level off, and then sharply take off (at MyMax). Yeah, you can FL size back down from here, but the primer pockets will loosen so fast as to have you constantly replacing cases. If not one of the more modern case designs, extraction will be difficult here, even with continued FL sizing.

    QL, especially when calibrated, is about as good for pressure predicting as math provides. But never forget that this is PREDICTING, and not actual measure. Even with Pressure Trace/strain gauge measure, the results are still a loose correlation to test barrel values (which your barrel is not).
    So none of us know what our pressures actually are.
    Then again, it doesn't matter what our pressures actually are.
    What matters are the LOCAL problems and how we associate them with OUR loads.
     
  7. bigedp51

    bigedp51 Well-Known Member

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    To get the most out of Quickload your actual case capacity and a chronograph is needed. And you change the burn rate in Quickload until the velocity matches the chronograph. Meaning you need a accurate starting point to calibrate Quickload.

    The rat turd in the violin case simply means a full length resized case vs the elephant turd in a violin case or neck sized case. Meaning the full length resized case body has "NO" guiding effect on the bullet.

    Your fecal debris statement has nothing to do with the amount of shoulder bump, and simply deals with case body clearance in the chamber.

    "a full-length sized case in which the neck is also fully sized. There is clearance at the neck and in the body of the case, the closest fit anywhere is the bullet in the throat. If the neck to bullet concentricity is good (although it needn't be perfect), then the bullet will find good alignment in the throat and the case body and neck will have minimal influence. Let's not forget that the base of the case is supported by the bolt face or the extractor to a certain degree as well; this is yet another influence on alignment. As you can see, there are several points from base to bullet that can have an effect. My procedure is to minimize the influence of those that I can control, namely the case body and neck, and let the alignment be dictated by the fit of the bullet in the throat and to some extent by the bolt's support of the base. Barring a seriously out of square case head, I don't think the bolt can have a negative effect on alignment, only a slightly positive effect from minimizing "case droop" in the chamber. Given that a resized case will usually have a maximum of 0.001" diametrical clearance at the web, this isn't much of a factor anyway.

    In conclusion, I believe that allowing the bullet to find a relatively stress-free alignment in the throat by full length sizing (including the neck) and turning necks to enhance concentricity gives the bullet the best probability of a well-aligned start into the rifling."

    The Rifleman's Journal
    Germán A. Salazar
     
    Last edited: Nov 5, 2018
  8. Mikecr

    Mikecr Well-Known Member

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    There just happens to be a related thread that popped back on the RADAR : https://www.longrangehunting.com/threads/brass-sticking-at-all-powder-charges.209490/

    It begins:
    He may have suspected this as a pressure issue, had it begun at about 90gr of powder. The problem could have presented that way.
    69 replies later (including some truly crackpot notions):
    Now he can get the action maker to send him a properly timed bolt.
    Any experienced gunbuilder would feel & see this bolt issue within a cycle or two. So no, 'GA', whomever that is, did not do a good job building his gun.
     
  9. 86alaskan

    86alaskan Well-Known Member

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    I was told by the builds that the symptom is exaggerated by the cases being brass. The rifle was test fired with premium ammo using nickel plated brass. I assume that the nickel would in turn be very easy for the bolt to break free, since the nickel doesn't have the tendency to stick in the chamber the same. Problem is, no one makes reloading brass in 338rum nickel plated
     
  10. snox801

    snox801 Well-Known Member

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    I was reading that thread. I’m getting same bolt lift as just moving bolt alone. It’s heavy but I knew that when I picked it up. It’s getting better and smoother as it shoot it. I’ve always used the rifle and brass to tell me when it’s maxed out. But i always here that “oh your above max according to quickload”. I always said quickload was a guide. Freebore and bullet design both can have big effects on pressure that can’t be in quickload. Just wanted to make sure I was on the right track.
     
  11. Mikecr

    Mikecr Well-Known Member

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    Freebore, bullet to land relationships, and neck tension are covered by starting pressure in QL. The bullet diameter and seated area can be entered as well as bore attributes(like bore area and length). Then there is weighting factor, friction adjustments, and powder burn parameters.

    A lot can be learned with local calibration of QL. In the hands of an experienced user, QL is more than a guide in that sound prediction is possible.
    For a past build, Using QL and RCBS Cartridge Design, I set the ideal cartridge capacity for XX bullet full case fill and a calibrated powder file for my lot of IMR4350 -while filling out my reamer print.
    I had used this powder for a couple different cartridges and had it dialed in well.
    After the build, and throughout testing from low to MyMax, the MVs were within 8fps of my build sheet. This, before sending the reamer order, with a wildcat there is no information published about.
    At the same time as designing the cartridge, I also measured bullets and calculated G1/G7 BCs for given altitude/expected air density conditions, and a confident guess of the velocity range my load development would settle at. Printed off a field click card. Damn if it wasn't dead on in the end(tested to 600yds). No revisions were needed.

    I know limitations of various software, but I also know the potentials with them.
    It's not really something to fear or dismiss.