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POI Question

Discussion in 'Uncategorized Threads' started by phirel, Oct 8, 2007.

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  1. phirel

    phirel TS Member

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    I would appear that most shooters like a POI between 60-40 and 70-30. We all shoot targets that are going up. My question is why do so many want 30-40% of the pattern below the bird where it would never have a chance of breaking the target?

    Would not a one ounce pattern above the bird have a greater chance of breaking the bird than a 1 1/8 oz pattern with 30-40% of the shot below the rising bird? Would not a 1 1/8 oz pattern with 40% of the shot below the bird reduce the effective pattern to nearly 3/4 of an ounce of shot?

    Pat Ireland
     
  2. zzt

    zzt Well-Known Member

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    I'd say:

    1) they don't. they shoot slow and want the bird centered in the pattern.

    2) yes

    3) yes

    I've noticed that a number of shooters at the clubs I go to take their birds at apex or even on the way down. Most shoot top singles with fixed ribs, so I'm guessing that old figure-8 bugaboo figures in this somehow. Others with low shooting guns move so fast to target they build in a lot of lead. Others aim. Aiming is easy with a 60/40 or 70/30 gun. Actually 75/25 is perfect for aimers IMO. It is damned difficult to aim with a 120/-20 gun (21" h @ 40yds).
     
  3. Rollin Oswald

    Rollin Oswald Active Member

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    Pat:

    Might the reason be to compensate for imperfect vertical pointing or sight pictures? Ideally, when a target is broken, the pattern is centered on the target. Where a gun shoots vertically is theoretically, the choice of the shooter and compensates for the swing speed, rate of target rise and reaction time.

    Rollin
     
  4. zzt

    zzt Well-Known Member

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    Joe, what you describe is not a high shooting gun. 2" high @ 13yds equates to 6"h @ 40yds. That's a 70/30 shooter. Even so, if you are having problems, it may be too high for you. Try lowering the comb 1/8" and see what happens.
     
  5. Rollin Oswald

    Rollin Oswald Active Member

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    Joe:

    It would seem that your holds at different heights for houses at different heights keeps your vertical swing speeds consistent.

    Rollin
     
  6. shot410ga

    shot410ga Well-Known Member

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    I tend to be a fast shooter from the 27. Per the computer I break the target at 39-40.5 yards out. So after trying everything from 50/50 to 100/0 I've found I will shoot over straight aways if I go any higher than 70/30 POI. It also means I Try to shoot under hard rights and lefts from #1 & #5. It works for me.
     
  7. hubcap

    hubcap TS Member

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    Pat - I believe the answer to your question is in the "error" that occurs from time to time when folks shoot.

    IF a given individual were to pull the trigger at EXACTLY the correct time on every target then your approach would have merit.

    However, we aren't shooting rifles we're shooting shotguns at moving targets which does provide an allowable margin of error while still putting enough pellets on the target to result in a broken target.

    Personally, I shoot an 80/20 pattern as I shoot a little faster than some and slower than others. This pattern height provides me with solid breaks and smoke while shooting singles and 25 yd handicap.

    Hubcap
     
  8. buckwheat

    buckwheat TS Member

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    IF all your target presentations fly true with no effect, from wind gusts or other outside influences, such as shooting over a draw then you are correct. If the targets are dancing, or being slammed due to wind then a percentage of your pattern below the centerline serves a good purpose. IMHO.
    Dan
     
  9. Rollin Oswald

    Rollin Oswald Active Member

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    Hubcap wrote: "IF a given individual were to pull the trigger at EXACTLY the correct time on every target then your approach would have merit." Does it though? Don't we always want the center of the pattern to hit the target?

    The merit of shooting a 60/40 or 70/30 (or whatever) gun is to put the center of the pattern on targets. Distance to targets and the swing speed used make the primary difference in the choice of POI.

    Rollin
     
  10. code5coupe

    code5coupe Member

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    "My question is why do so many want 30-40% of the pattern below the bird where it would never have a chance of breaking the target?"

    Why would anyone want 60 to 70% of the pattern above the bird where it has no chance of breaking the bird?? Since only shot that contacts the bird has a chance of breaking it, we should all be shooting guns that pattern 0-0.
    By George, I think I've got it!
     
  11. zzt

    zzt Well-Known Member

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    Joe, the old 60/40 and 90/10 notions were at a standardized 40 yard distance. Even so, they really did not have anything to do with where the pellets fell. If you take the nominal 30" pattern at 40 yards (the old standby for years) and center your POA with the pattern, that was considered 50/50 or flat. So 15" of your pattern was above your POA and 15" was below. So if your POI was 3" above your POA @ 40yds you had 18" of the pattern above POA and 12" below. That's 60% above (18"/30") and 40% below (12"/30"), so it was called 60/40. Raise POI by another 3" and you have 70/30.

    The point is it was the area of the pattern that determined nominal distribution, not where the pellets actually fell. Just to blow your mind, a Beretta field gun I used to have threw round patterns. Half the pattern area from one barrel was above the POA and half below. The kicker was the pellet distribution favored the lower half of the pattern. So was that a 50/50 shooter (by area) or a 40/60 shooter (by pellet distribution).

    Now take your statements. Your gun shoots 2" high at 13 yards. That's a precise measurement that can be extrapolated to different distances. You also say when you shoot at 35 yards about 90% of the pellets are above your POA. That doesn't really mean anything. If you called that a 90/10 shooter, then put in a more open choke and shoot at the same yardage, did that gun become a 80/20 shooter, or a 70/30 shooter just because you changed chokes and threw wider pattern. No, the POI remains the same.

    If you measure from the center of your pattern at 35 yards I think you'll find it is about 5" to 5.25" above POA. That's a 70/30 shooter measured the old way. If you really did have a 90/10 shooter, your POI would be 10.5" above POA at 35 yards. So it really is better to use dimensions. Everybody understands what 2" high at 13 yards means, or 6" high at 40 yards. Almost no one gets 60/40 right, because everyone thinks it means something different.

    If Pat wanted to be really precise, he could have said 3" above POA at 40 yards (60/40) or 6" above POA at 40 yards (70/30).
     
  12. Shooting Coach

    Shooting Coach Banned User Banned

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    Always being respectful of those perfect shooters out there, sometimes I overswing the gun a little and might even have the bead over the bird! :eek:))

    I would like the pattern to cover that bird and get enough of it to get an "X" on the score sheet!

    70/30 works for me on singles and caps. My backup 870 Comp shoots 90/10, but I still use the same sight picture for it and my K-80 Unsingle.
     
  13. phirel

    phirel TS Member

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    zzt- I fully agree with your position that the POI should be measured as the distance from the POA. However, some things, even if they are not accurate, are so ingrained in our minds it is nearly futile to try to change them. Changing the description of where a gun shoots from a % above and below the POA is much like convincing others that Frankenstein is the name of a normal looking Doctor who created a monster who was not named Frankenstein.

    Pat Ireland
     
  14. hmb

    hmb Well-Known Member

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    You need part of the pattern below the bird because birds do not fly in a straight line. Also birds can fly, but, flies can't bird. Do you understand Pat? HMB
     
  15. Trapgeezer

    Trapgeezer TS Member

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    If 100% of your pattern always passed above the target, how would you ever hit it. POA has to be factored into this, no? Is it not "what it looks like rather than what it is"?
     
  16. hoggy

    hoggy TS Member

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    I have my gun set 90/10. Cannot speak for others.
     
  17. smsnyder

    smsnyder Well-Known Member

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    110% high. as long as i stay under target it WILL break. 99% of my trap targets are rising. does not apply to other clay games were i like 50/50% pattern.
     
  18. jim brown

    jim brown Well-Known Member

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    Pat,

    Like most older shooters who watched the Texas all-Americans break the heck out of targets with the super high shootin guns I have tried it all. I seem to settle somewhere around 90-10 or 100-0 but I have experimented with guns that shoot much higher. The problem with the thinking lies in the different angles. On a bird right down the barrel we simply come up somewhere below the bird or touch it with the bead and let her go. High shootin barrel takes care of the lead and the target puffs. Next bird you get is a hard angle either way but a full angle off post 1 or 5. You swing out after the bird and give it the proper left or right lead but now with the high shootin gun you have to put the bead level with the bird not in line with the target path. If you swing the bead in line with the target path you have now compounded your vertical lead. You put the vertical in and the barrel put the vertical lead in too. If your gun shoots 100-0 or higher you just missed the angle. To shoot angles with a high shootin gun you have a very complex lead on angles but a simple shot on the straight away target. Somewhere around 60-40 or 70-30 you have a gun that can shoot straight away targets without covering them with the barrel and you can still put the bead on the target path and break a full angle target.

    Having said all of that garbage I still shoot a handicap barrel that is about 100-0. What was that they said about old dogs?

    jim brown
     
  19. phirel

    phirel TS Member

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    Hooligan- My numbers (I rounded them) come out just a little different from yours primarily because I included an additional factor, the distance from the center of the bore to the top of the rib.

    2 inches high at 13 yards = 6 inches high at 39 yards, minus 3 inches (shot fall due to gravity) plus the distance from the center of the bore to the top of the rib times 3 (1 inch X 3 = 3). This means that 2 inches high at 13 yards would actually be 6 inches high at 39 yards and should be have about 70% of the pattern above the point of aim at 39 yards.

    You need to include the distance from the top of the rib to the center of the bore. These two lines are not parallel.

    Pat Ireland
     
  20. zzt

    zzt Well-Known Member

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    Barry, the shot drop is accounted for. Remember, the barrel is below the LOS (Line of Sight) so if you zero at short yardage, the barrel is actually pointed up. The shot rises, hits the zero yardage, continues to rise, then begins to fall, then eventually recrosses the LOS. Works just like a rifle, except the distances are much shorter.

    Here is an excerpt of the trajectory post i made a year or so ago, using Winchester data from Shotgun ballistics for Windows.

    Trajectories for #7 1/2 shot zeroed at different yardages from an unsingle.

    Each line will be in the form of:

    Zero yardage//rise or drop at 20yds/25/30/35/40/45/50//Recrosses Line of Sight yardage

    13yds//.55"/.91"/.94/1.03/.79/.45/-.18//48yds

    14yds//.41/.74/.77/.8/.53/.16/-.51//46yds

    14.5yds//.34/.66/.67/.68/.39/0/-.69//45yds

    15yds//.30/.60/.60/.60/.30/-.10/-.80//44yds

    16yds//.15/.41/.37/.34/0/-.44/-1.18//40yds

    If you are looking for the absolute flattest trajectory, 14.9 yards between the muzzle and the paper is perfect.

    The 13 yard number started as a convenience for one of the gentlemen who popularized this method. As it happens, multiplying by 3 gives you the offset at 40 yards, so it became popular. Personally, I like 15 yards better, because it gives me a more accurate picture at singles and handicap target distances.
     
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