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optimum pattern percentage

Discussion in 'Uncategorized Threads' started by ColBuckShot, Mar 2, 2008.

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  1. ColBuckShot

    ColBuckShot TS Member

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    Im looking for what is the most favorable percentage of shot in a 30in pattern at the medium yardage I break clays. For example, is a 90% pattern better then tightening the choke and getting 100% at that yardage. I have patterned and broke birds from the same yardage with all chokes from .020 to .040 constriction. What percentage is generally considered the optimum for any particular yardage(known) one regularly breaks birds, keeping in mind this could pertain to doubles or handicap as well. It is the optimum percentage im looking for. I have found this site most helpful, thanks to all who contribute.
     
  2. tcr1146

    tcr1146 Well-Known Member

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    Don't hold me to every word, but I believe Bruck Buck (technoid) from Shotgun Sports has to his satisfaction anyway, proven that 75-80% at the range you are breaking targets to be the optimum pattern?! For example, if your 16 yard targets are being broken at 32 yards, you would want a 75-80% pattern at that range, etc. If a 27 yard shooter, and break them at 43 yards, again if you can achieve it, 75-80% would be ideal according to him! Tom Rhoads
     
  3. ColBuckShot

    ColBuckShot TS Member

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    tcr1146
    Exactly what I was looking for, buy yourself a beer and send me the check.
     
  4. tcr1146

    tcr1146 Well-Known Member

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    I would join you! Tom Rhoads
     
  5. zzt

    zzt Well-Known Member

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    What Tom say Bruce Buck suggests is correct. Tom Wilkinson, an excellent barrel smith says 80% at target range. I say 85%, because that is a good compromise between the best chance for a hit, while leaving a little margin for error.

    I've posted the whole bit before, but here is an excerpt using data for just one load. For a 1 1/8oz load of #8 and a 100% chance of a hit with at least one pellet, here are the diameters of the 100% effective patterns at different PEs.

    Remember, these are diameters at target distance, whatever you choose that to be.

    75% PE: 3.2" dia.

    80% PE: 9.6"

    85% PE: 12.4"

    90% PE: 14.2"

    95% PE: 15.4"

    99% PE: 15.4"

    So here is how you use this data. Say you are looking for the best choke for singles. Let's also say that you had a friend watch you shoot, and he estimates you take your singles targets at 30 yards for straight aways and 34 yards for hard angles. As I recall, you are a slow shooter, so maybe it is 32 and 36 yards for you. Even so, the logic is the same. If you are consistently taking targets between 30 and 34 yards, go to the range and pattern at 34 yards. Decide how large you want your sure kill diameter to be, and pick the choke that gives you that Pattern Efficiency. The shorter distances will take care of themselves.

    The beauty of this method is it eliminates all the variables. Shoot a cheapo load with soft shot? OK, you'll need a tighter choke. Shoot a really good shell? OK, maybe you can open up a touch. The PE % will tell you, and there is no hiding the facts.

    So if your load and choke gives you 85% at 34 yards, the same combo will give you 95% at 30 yards. Personally, I'd go for 90% at 35. That would give me 97% at 30, and is right where I want to be. My .022 choke does exactly that, and still gives me enough smoke so I know when I am centering targets.
     
  6. ColBuckShot

    ColBuckShot TS Member

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    zzt come back, PLEEEEEEEEEEEEASE
    I dont understand the diameters.
    ex. Decide how large you want your sure kill diameter to be.
    and: 85% PE: 12.4" what is the 12.4" mean
    HELP!!!!!!!!!!!!
     
  7. ColBuckShot

    ColBuckShot TS Member

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    Can anyone explain what these diameters are zzt is talking about.
     
  8. miketmx

    miketmx Well-Known Member

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    The article at the link above is by Bruce Buck commenting on the research by John Brindle. Neil Winston and Dr. A C Jones have done a lot of patterning with computer software to aid in the pellet counts and both pretty much agree with the findings of Brindle.
     
  9. Pocatello

    Pocatello Active Member

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    Most ballistics experts claim that a shotgun pattern is normally distributed in terms of position measured from the center of the pattern. What I think they mean is that the angle measured from the center is uniformly distributed, while the distance falls off normally (most of the pellets are close to the center, while the number falls off the further away from the center you get, in a bell-shaped distribution). I know that when one does simulated patterns using those criteria they look quite like real patterns I've observed. If the model is valid, one could ask the question of pattern effectiveness in several ways. One way I've chosen to ask it is in terms of likelihood of breaking a target with a "fringe" hit. If one draws a circle about the center of the pattern, it can be divided into two parts of equal area, an inner central circle, and an outer annular ring. No matter what the pattern density in the whole circle (i.e. no matter what choke), the inner circle will always have a higher probability of a hit than the outer ring (i.e we'll break a lot more targets if we center our pattern on it - DUH!). The question is what density in the whole circle maximizes our chance of breaking a target in the outer ring? The answer does not depend on the size of the circle - obviously Leo Harrison has a much better ability to keep his targets within a given circle than I (i.e. he points a lot closer than I do, so his effective circle has a smaller radius than mine), but he doesn't keep them all perfectly centered all of the time. It turns out that one can prove mathematically that for any given circle, the pattern density in the whole circle that maximizes the pattern density in the outer annular ring is about 76%. This pattern density gives slightly under 60% in the inner circle and just under 17% in the outer ring, so you are still a lot better of centering your target.
     
  10. zzt

    zzt Well-Known Member

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    CBS, the sure kill area is the diameter of the pattern that guarantees you a 100% chance of a 1 pellet strike on the target.

    For an 85% PE (Pattern Efficiency- 85% of all the pellets fall within a 30" circle) the diameter of the pattern that will always break a target is 12.4".

    Sometime or other, way back in the distant past, some yahoo decided that nominal patterns were 30" in diameter. I suppose they were shooting at game or big targets. At any rate, for ATA targets, the largest effective pattern you can hope for using legal shells is about 21" in diameter. I don't care what choke or ATA trap load you are using, that is the case. The area between 21" and 30" has so few pellets any hit is pure luck. However, if you decide to use #9 shot, the diameter increases a bit.

    So let's say that you have a load and choke combination that gives you 85% PE at your target distance. That means you have the same 21' diameter effective pattern that can be counted on to break targets most_of_the_time. The only area you can count on to break targets all_of_the_time is the central 12.4" diameter. Said another way, if you misspoint by less than 6.2" at target distance, you will break the bird. If you misspoint by 11" you still have a reasonable chance to break the bird, but it is not guaranteed.

    If you decide to use a choke that gives you 95% PE, then the central 15.4" of the 21" diameter effective pattern will give you a certain break. So you can misspoint by 7.7" and still be assured of a break.

    Translating a lot of gobbledygook, Bruce Buck (whom I admire) uses a statistical benchmark that equates to a 95% chance of a one pellet hit. That means you will miss 5 out of every 100 perfectly pointed targets. That's great if you are a Sporting Clays shooter wanting the best odds. It's not great for a trap shooter who needs a perfect score just to make it to the shoot-offs. Trap shooters like certainty, so they pay attention to what I am calling the sure kill area.
     
  11. phirel

    phirel TS Member

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    Pocatello and zzt have accurately described my dilemma. I want the largest sure kill area (tight choke) but do not want to give up any more lucky fringe hits than necessary. If I increase the likelihood of getting a lucky fringe hit I have to decrease the size of my sure kill area. If I increase one, I have to give up another, and I want both.

    Pat Ireland
     
  12. zzt

    zzt Well-Known Member

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    1 1/8oz #9 @1290fps Pat, or change the rules to allow 1 1/4oz.
     
  13. ColBuckShot

    ColBuckShot TS Member

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    Thanks to all who contributed and especially zzt.
    Perhaps I should have patterned my head instead of my gun.
     
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