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Neil's POI Test?

Discussion in 'Uncategorized Threads' started by EXFDX, Nov 10, 2007.

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  1. EXFDX

    EXFDX Member

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    Does anyone either remember Neil Winston's recipe for or remember the tiitle of the thread(s?) where he discusses the ingredients of his personal POI test? I think I remember 13 yards and three or four test shots. Anyone remember the details or point me to a thread? I don't think it was a thread title but rather a response within another separate thread.

    Thanks,

    Steve Oehmen
     
  2. setter

    setter Member

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    Here it is!
     
  3. Neil Winston

    Neil Winston Well-Known Member

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    That's a joke, right Jack? Anyone else know anything about something like this, starting with "Is it possible?"

    Neil
     
  4. setter

    setter Member

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    Is it possible? Yes, but about as likely as a trapshooter robbing a lemonade stand.

    Jim
     
  5. EXFDX

    EXFDX Member

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    Thanks so much -- you all are GREAT!! And who's "Jack"? And I'm not tracking on "Is it possible…" I'm still trying to figure how adjustable ribs affect POI, but I'll keep working on that. I guess my POI tests will tell me what I need to know.

    Again, thanks everyone so much. I can't imagine being able to tap into so much expertise so quickly as you can on Trapshooters.com

    Steve Oehmen
     
  6. RunGunIPSC

    RunGunIPSC TS Member

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    I don't believe that the 13 yard distance provides a valid POI .
    As proof,I offer the following;Is there anyone out there that breaks a trap target @ 13 yds from the muzzle. Now I do admit that certain skeet targets can be shot at that distance & an occasional SC target also.
    Further,it only may give POI & not a true pattern which is equally inportant.
    I feel it is best to pattern at the approxmate distance for the game,ie 35-45 yds for trap,22-25 yds for skeet & about 20-50 yds for SC.
    I ABSOLUTELY hate the walks & changes of cardboard/paper,but at that I have something very positive.
    Tom
     
  7. phirel

    phirel TS Member

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    Tom- The POI is not directly related to the pattern. They are two different things. It is my opinion that it nearly impossible to measure the true POI much past 15 yards. Measuring the POI at 13 yards makes it a bit simpler to extrapolate the POI at 30 yards.

    The only accurate way I know to accurately measure the POI form a 30 yard pattern is to photograph the pattern and use a computer program.

    Pat Ireland
     
  8. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    "I don't believe that the 13 yard distance provides a valid POI ."

    Tom, yes it does give you a valid POI at 13 yards. That distance will tell you if the barrel shoots straight horizontally and vertically. Once you've done enough patterning at that point and various distances, an overall picture of pattern performance will develop, somewhat with more experience. My take on the two 13 yard patterns shot and pictured above, one was pulled right of the bullseye and the other right on. (guess)

    Raising the front bead will cause both shotguns and rifles to shoot patterns or bullets LOWER if aimed at a cross or dot. Just the opposite for lowering the bead or sights on a rifle. A blade elevator is used on rifles to raise or lower POIs, on shotguns, the stocks comb is the "elevator" for shooting moving targets. Lowering the front of the rib (bead) only will also but it requires a slight difference in eye position as related to the stocks comb to work as intended. That isn't the ideal way of changing a shotguns vertical POI in my opinion since it changes the eye (head) position some.

    Pat, the pattern optimizer is a great program, however, good workable patterns could be read with experience long before Andrew came up with it. It does save a lot on counting and guessing how many pellets are in each quadrant. I read my patterns on paper by eye, then on how well they break clays before they pass muster. I can tell you within a half inch where my (workable,acceptable to me) pattern centers are located at 30 yards from the bench and that's close enough for successful shotgunning. Hap
     
  9. RunGunIPSC

    RunGunIPSC TS Member

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    I guess I look at at POI differently than others. POI is truly fixed,dependent on the ammo used,barrel dynamics,etc. I use a perfectly flat rib site picture,ie one only sees the front bead. I use a 3" orange dot @ 40 yds(25 for skeet choked guns.) I shoot from a bench,sitting & holding the gun normally in my hands,butt against the shoulder,front hand on a sandbag. This allows the gun to show some semblence of normal recoil & me a good site pic. I can,with this method,fix POI within 1/2" @ 40 yds. I have shot 1000's of patterns with a lot of guns in 35 years this way. My record for 1 gun was 110 shots in a 682,fixed choke. I could never get the gun to shoot center vertically,always went left or right,low or high & move as much as 12-15" between loads.
    I agree completely that one can change the POI by comb,seeing more rib,etc.
    But I want to know exactly where that bbl will shoot with the LOADS I shoot.
    And by using the set-up above,I can go back any time & get the repeatability with any gun or load I have shot.
    I have found it takes me 3 shots to begain to see the POI. And I have the advantage of pattern determination also.
    I also agree about the moving gun,wind,etc on POI & pattern. See The Modern Shotgun by Major Sir Charles Burrard for the very best on this.
    One does what works best for himself. Tom
     
  10. phirel

    phirel TS Member

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    Hap- I have no doubt that you are better at identifying the center of randomly spaced holes in a pattern than I am. I just can't decide where the center is with any certainty.

    Tom- I focused in on one sentence in your post "I have found it takes me 3 shots to begin to see the POI". Does this indicate that you are shooting several rounds at the same target and then reading the dense cluster? If so, it can easily be shown by shooting once at 10 different targets, you are reading the "mean" center of several point of impacts produced by aiming errors. At 13 yards, a clear hole is present indicating the POI. If you do this 10 different times, several aiming errors become apparent even at 13 yards. These errors are magnified 3 times at 30 yards.

    Pat Ireland
     
  11. RunGunIPSC

    RunGunIPSC TS Member

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    Pat,
    I only shoot 1x per paper. I also look at the patterns. Yup,a bummer gathering all that cardboard. Body shops & auto glass shops usually have a good supply. I am down a bit on boards now. Only have about 100 in stock. YES,YES,YES I hate all the work involved. But I have found about 50% of all bbls do not shoot to POI and/or have pattern problems. I can tell some real stories here. Have I had my work validated? Yes. By no less than Tom Wilkinson. I had an MX-8 that had been shot 2 boxes before I got it. Had Briley Thin Wall in it. I shot about 60 patterns & could not get a good pattern or POI. Sent it to Tom,he spent 5 hours trying including cutting his own tubes,sent it back & said "Forget it"(yup,I paid him for his time.) That 50% inc all the good makes,too. Perazzi,Krieghof,Beretta,Belgian & Japanese Brownings,Remington,Winchester,etc. In fact I have 6 guns waiting to pattern,3 Belgian Brownings,2 Perazzis & a Ljutic. And I just had cortisone shot into both knees. Guess I need to hire an assistant to run targets. Tom Lobonc
     
  12. phirel

    phirel TS Member

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    Tom- I did read something into your post that was not what you intended to communicate. Sorry about your knees. Getting up and down from the bench is probably as difficult as walking out to the pattern boards. Cortisone may help the symptoms but will not fix your knees. But, I think I know something that will fix them.

    When I go down to the Dixie Grand I will ask Jerry B. about a special fountain in Florida discovered by an early Spanish explorer. It is supposed to be on South Ponce de Leon Ave. I will send you a bottle of the water if I can find the right road.

    Pat Ireland
     
  13. jhh

    jhh Member

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    Here is a thought and technique that I have used for a long time with my guns. This was passed on to me from Billy Purdue mabee 25 years ago.

    POI as described in the threads I just read seems to me do with the POI of the shotgun, which is the first thing that we need to know. Does it shoot to a POI that I call a mathmatical POI, ie: could be proved by calculation, and does it do so consistantly. Finding this out tells one that the gun is or is not going to preform as one expects it to. To me that is why we shoot a rifle for a group, to see what we can expect it to do on a consistant basis.

    After finding out that the gun is satisfactory in it's preformance I would take an old bed sheet and put it on the pattern frame, useing the shells I intended to use in an event I would stand and try and simulate my shooting "hold and swing" and fire at the center of the sheet untill a torn out place appeared, that torn out place being the POI of the gun when combined with the shooter. This sometimes took 20 to 25 shots. When I say swing, I always let off a shot with the gun moving. Shoot at the center bringing the gun from the left, from the right, and from below the dot. Don't know if this would be helpful to anyone else but I think it helped me through the years.
    John Hancock
     
  14. phirel

    phirel TS Member

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    John- You have described an interesting method to determine where a gun shoots for you. When testing a gun for POI at 13 yards, what we are really doing is checking where the gun shoots (high, low, left, right). This may not tell you where you shoot the gun. At 13 yards, my gun shoots very high (5.5-6 inches). When I am chasing a target at 40 yards, I am convinced that I do not shoot the gun as high as the gun shoots. One of the most valuable things we can learn from the 13 yard POI test is if the gun shoots right or left. Secondly, a very high or very low POI can tell us something. Beyond that, I do not get too concerned about the POI. Some may be able to distinguish between a gun that shoots 2 inches high at 13 yards and one that shoots 3 inches high, but I can not do that.

    Pat Ireland
     
  15. fearlessfain

    fearlessfain TS Member

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    i have tried every one of the poi methods mentioned on this forum and i say if you want to spend endless hours at the pattern board go ahead. but if you want to do it with one shell, shoot the board at ten (not thirteen) yards from a stationary rest and squeez it off like a rifle. this will leave a spread of approximately six inches. you will be able to tell exactly where the point of impact is. this method is for the choked barrels.(put an e on the squeeze)
     
  16. AAtrap

    AAtrap Well-Known Member

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    Tom L. I have a friend who owns a crematory. I get the bottom of the cardboard boxes they use to cremate a body in to do my patterning. I cut the two end flaps of to use for checking POI. I can get three on each end flap and then cut the remaining piece in half and draw two 30 in. circles on those. Might check it out if you have a crematory close. Steve
     
  17. phirel

    phirel TS Member

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    fearlessfain- The only advantage of using 13 yards to measure the POI is the simplicity of converting the 13 yard POI to a ca. 40 yard POI.

    1 inch high at 13 yards = 3 high at 39 yards. Less 3 inches fall due to gravity + distance from center of bore to front sight times 3. The gravity factor is a bit more cumbersome if you use 10 yards.

    Pat Ireland
     
  18. CharlesR1100

    CharlesR1100 TS Member

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    All...where do you get the 3 inch fall figure for the 13 yard gravity field effect? Who or what published that 3 inch factor?

    If the fall, due to the gravitational field, was 3 inches in 13 yards, would it be 9 inches in 39 yards? That seems a bit too much.

    My guess is that the 3 inch number is just a theory, a working or "field" number, not proven.

    If the 3 inch gravity fall figure is just a guess, then the 13 yard POI is also just a guess. But probably no worse than any other. But no better.

    Further, normal trap shots are not level with the ground. The gun is pointed up. That would reduce the fall at 13 yards and latter.

    Given the very short ranges at which the targets are taken, I would doubt gravity would have much measurable effect on the POI.
     
  19. Avaldes

    Avaldes Well-Known Member

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    The fall of the shot at a range of 13 yards, assuming you shoot about 1200 ft/sec, works out to 1 inch. So if you go from 13 to 39 yards, the fall is roughly 3 inches. This assumes the shot doesn't slow down, which in reality will increase the drop slightly.

    Also, the effect of gravity is constant, whether you point the shot up or keep it horizontal.

    -Aaron
     
  20. CharlesR1100

    CharlesR1100 TS Member

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    Aaron...who reports that the fall is 1 inch in 13 yards? Where does that number come from?

    Fired 1 1/8 oz. slugs would not (I think) fall 1 inch at 13 yards. Shot probably not either. So where does that 1 inch number come from?

    I do not know, but I think shot would travel much further than 13 yards before dropping 1 inch. If so, the formula is wrong.
     
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