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Good shot, bad shot and central thickening?

Discussion in 'Shooting Related Threads' started by mrskeet410, Dec 30, 2011.

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  1. mrskeet410

    mrskeet410 TS Member

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    Is there a difference in the central thickening ratio between hard shot and regular grade shot? And if you think there is, what lead you to that conclusion?
     
  2. Cooter

    Cooter Member

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  3. Ajax

    Ajax Well-Known Member

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    At what yardage?

    Ajax
     
  4. birdogs

    birdogs TS Member

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    At least 2 to 1.
     
  5. Bvr Tail

    Bvr Tail Well-Known Member

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    Yeah, 2 to 1, that's how I mix my stiff drinks before I start a a new thread!!
     
  6. Stl Flyn

    Stl Flyn Well-Known Member

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    Yep, two to one. Two parts ice, and one part Bombay Sapphire gin, with just a wiff of dry vermouth. Shake the sh84 out of it, until it is to cold to hold on to, and strain into a frosted Martini glass. Add a couple of gently speared Jalapena stuffed olives, (Try not to splash, as not to be accused of alcohol abuse), and sip. Ahhhh, perfect.
     
  7. Unknown1

    Unknown1 Well-Known Member

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    Don't know about shot but the current trend in thickening in government with the current supervior/subordinate ratio at mid-level standing at 1:7 and at 1:7 at median indicates a gradual strangulation and a decreasing efficiency as the bulge grows.

    MK
     
  8. birdogs

    birdogs TS Member

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    Unless the antimony content is greater than 6% in which case the numerator is doubled for each percenmtage point in excess of 6%.
     
  9. rocketman100

    rocketman100 TS Member

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    No, shotshell patterns are distributed according to the Rayleigh distribution. Central thickening is just a way of noting that the center of the pattern always has more pellets per square inch than anywhere else. Hard shot may improve choke effect slightly. For the real data on this subject, get a copy of Dr. A. Jones's book, Sporting Shotgun Performance.
     
  10. sliverbulletexpress

    sliverbulletexpress TS Member

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    The endometrium demonstrates a wide spectrum of normal and pathologic appearances throughout menarche as well as during the prepubertal and postmenopausal years and the first trimester of pregnancy. Disease entities include hydrocolpos, hydrometrocolpos, and ovarian cysts in pediatric patients; gestational trophoblastic disease during pregnancy; endometritis and retained products of conception in the postpartum period; and bleeding caused by polyps, submucosal fibroids, endometrial hyperplasia, or endometrial adenocarcinoma. Other findings include tamoxifen-associated changes, intrauterine fluid collections, and endometrial adhesions. Although ultrasound (US) is almost always the first modality used in the radiologic work-up of endometrial disease, findings at sonohysterography, hysterosalpingography, magnetic resonance imaging, and computed tomography are often correlated with US findings. It is important to understand that the appearance of the endometrium is related to multiple factors, including the patient’s age, stage in the menstrual cycle, and pregnancy status and whether she has undergone hormonal replacement therapy or tamoxifen therapy. Accurate diagnosis requires that these factors be taken into account in addition to clinical history and physical examination findings. Other than that I don't know.
     
  11. rhett1977

    rhett1977 Member

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    7.5's or 8's
     
  12. Neil Winston

    Neil Winston Well-Known Member

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    My response to the many things I've read about central thickening has been that its stability has been vastly, vastly oversold. Oh yes, down in the fine print, generally, is the caution "on the average" but little about the variability has been made clear.

    Central thickening is, as Rocketman says, a number attached to the general fact that real trap patterns are hot in the center; all of them are. Commonly in a 40-yard full-choke pattern the "pellet density", that is, the number of pellets per square inch, will be 1.5 to 2 to 2.5 times as high in the inner 20-inch circle of the pattern as in the surrounding 20-to-30 inch torus. People who say that this or that gun or powder or whatever produces "even" patterns just haven't counted the pellets, that's all. There aren't any even patterns.

    But the statistic is disappointingly variable, It's nothing for a single 10-shot string to to have patterns which vary from less than 1.5 to more that 2.25 or more. Based on O&T, I actually had data sheets made which tracked the central thickening (called and calculated otherwise, but the same thing at heart) of individual shots, since that's the way they seemed to say it worked. You wouldn't get three shots into a test before realizing that none of the calculations, nomographs, and so forth worked at all. A barrel which rated "good" on the first shot would be "average" or "very good" on the second and the third would be something else again but it was always the same barrel.


    Central thickening is, for all its faults, the only "evenness" metric which is at all useful. Lowry uses it to determine whether patterns are Gaussian or not but I can't see why that's very important (relative to a particular gun or load) or, even, why I would want to know.

    So, Mr. Skeet, the answer is ... what? Rather, what you you need to know to answer your question of the effect of shot hardness on central thickening? First you would have to know what is "typical" of one of the ends of the hardness continuum. It will be a range of numbers, with central thickening being highest when pattern density is highest, less when patterns are more "open." I'm slowly collecting that data all the time and it will eventually be a graph relating pattern percentage to central thickening. It's a ragged graph, but there will be a line of best fit and since there will be more than a thousand patterns contributing data, it will be solid.

    Then I just take my soft-shot data and see how they fall in relation to the hard-shot data. I may be able to that by next spring, so if you are in a hurry, I'd suggest you do it yourself.

    As I say, central thickening is closest thing we have to describing "pattern evenness" so it's a project worth doing. Just expect way, way more variability than you have ever been warned about except here.

    Neil
     
  13. rocketman100

    rocketman100 TS Member

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    Good explaination, Neil. I'd add one thing that may not be obvious. Due to the Gausian nature of patterns (Rayleigh, to be exact), an open choke pattern (skeet) will be equally "hot in the center" at 10 - 15 yards closer to the gun than a trap (full) pattern. Neil's point about variability is the primary reason this issue has not, to date, been fully resolved. There have been just too many patterns needed for people to do the work. Fortunately, Dr. Jones has solved the hole counting problem whit his computer reader and statistical analyzer.
     
  14. Neil Winston

    Neil Winston Well-Known Member

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    I have one skeet pattern here. Is that enough?

    Actually, there are some interesting things about central thickening that may be true. While I am an uncompromising hardliner on the basic randomness of patterns, (so I don't count "holes") I'm not at all sure that claims like "Green Dot produces higher central densities than Red Dot when overall pattern density is taken into account" are untrue. I think that may be a powder differences which is reproducible. Again, the whole data set has to be organized and then we can see what, if anything, falls outside the expected range by enough to be called "a different result."

    Neil
     
  15. Dr A C Jones

    Dr A C Jones Member

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    rocketman100, Please recall this figure:

    <image src="http://www.shotgun-insight.com/publicBookPics/fig151ppp.png">

    The debate shouldn't really be about whether the distributions are Guassian or not, but rather how close they are to the pure Gaussian.

    There will always be a small central bias because the centre of each pattern is deduced from the pattern itself rather than the true POA of the gun. Ideally, if one wanted to investigate this deviation from the Gaussian one would fix the gun and measure all patterns from the POA.

    I'll also reiterate that there's no overwhelming practical need to know this information. For trap, it's the centre 10-inch or 20-inch circle that does the business, so just measure the pellet count therein directly. 30-inch PEs and my 75% pattern diameter are just an abstraction that unfortunately allow some deviation between the assumed model for the metric and the part of the pattern that does most of the work (in the trap case). Just measure the bit of the pattern you are interested in and then there can be no debate about distributions.

    Andrew.
     
  16. trapshootin hippie

    trapshootin hippie Well-Known Member

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    My ex-wife suffered from a severe case of "central thickening" I believe.


    GneJ
     
  17. mrskeet410

    mrskeet410 TS Member

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    Dr. Jones and Mr. Winston - Thank you for your posts. I hoped you would.

    I guess my real question is this - Is there a practical difference between a 70% pattern with soft shot from x.xx choke and a 70% with hard shot from a y.yy choke?
     
  18. mrskeet410

    mrskeet410 TS Member

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    Neil - Thank you for reminding of the high variability of shotgun patterns. That variability makes eyeball patterning mostly less than useless.
     
  19. rocketman100

    rocketman100 TS Member

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    Andrew, that is a good reminder. I was thinking along those lines. Unless I am mistaken, there is no "central thickening" characterstic other than more choke effect producing a tighter distribution curve. I have no objection to the use of "central thickening" as a lay term for the effect of tighter choke. However, I'd discourage using "central thickening" to describe an independent characteristic of a pattern. For example, to say, "Pattern X is just like pattern Y, except X has greater central thickening," ignores the fact of patterns following Rayleigh (a special case of Guassian) distributions. Conceptually, to say, "I'll use full choke as it has a thicker center than IC," would be correct.

    While not a termonology snob, I think it worthwhile to try to discourage use of conceptually incorrect terms and misuse of terms that lead to misunderstanding. As an example, one often hears, "Thhis gun has perfect balance!" The actual (hidden) meaning of this phrase is, "I really like the way this gun handles." The implied concept is that guns posses a physical property of "balance" that can be used as summative for handling and can be expressed judgementally. On the other hand, balance, meaning the teeter-totter point, is a physical fact of the gun and is quite useful in understanding the handling properties of the gun. In this case, balance is a fact and like length of pull, would not be judged as good/bad, other than on an individual shooter basis. You don't usually hear, "This gun has perfect LOP."

    DDA
     
  20. cubancigar2000

    cubancigar2000 Well-Known Member

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    ask Obama, he's your guy
     
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