1. Attention: We have put together a thread with tips and a tutorial video to help with using the new software. Please take a moment to check out the thread here: Trapshooters.com Tutorial & Help Video.
    Dismiss Notice

POI Question & Defination

Discussion in 'Shooting Related Threads' started by Kolar233, Jun 24, 2013.

  1. Kolar233

    Kolar233 TS Member

    Joined:
    May 10, 2012
    Messages:
    52
    How is a gun defined as shooting 60/40 - 70/30 - 80/20 as it relates to the POI ? By that I mean is 70/30 4" high at 13 yds or 12" high at 40 yds ? Just what are those relationships for the POI's ?
     
  2. Trap2

    Trap2 Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,685
    Location:
    Redding, California
    Neil Winston's rule of thumb is this:

    1" high @13yds= 3" high @40yds 60/40%

    2" high @13yds= 6" high @40yds 70/30%

    3" high @13yds= 9" high @40yds 80/20%

    4" high @13yds= 12" high @40yds 90/10%

    5" high @13yds= 15" high @40yds 100%

    This will get you as close as you can get.... Dan Thome (Trap2)
     
  3. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Dan, please, please, call it anyone's definition but mine! I blame Kay Ohye for it since it's in "You and the Target", an otherwise fine book. For it to be true, the following conditions would have to be true.

    1. Patterns would have to be even. They aren't; they are hot in the center.

    2. Patterns would have to be square. They aren't, they are roughly circular.

    3. Gravity would have to give a mulligan to shot. It doesn't.

    And for us to be even talking about it there would have to some earthly use for all this "Percent high" mumbo jumbo and there isn't. It's all nonsense; it's all worthless. Talk about inches, not "percents high."

    After all, the "%-high" guys are just making it up - if they knew where their guns shot they would say "Five inches at 40 yards." But they have no idea, so they say " I like to set my handicap gun up for 80/20" which they have not done and wouldn't know what it meant or how to do it anyway. You wouldn’t want to be be lumped in with all those flakes, would you, Kolar 223??


    Stick to inches.

    Neil

    If you don't believe any of this, just ask someone who quotes the POI of his gun a some percent "What's that in distance high?" Most won't even understand the question. And they would if they knew where their gun shot. They don't . They are bluffing.
     
  4. Trap2

    Trap2 Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,685
    Location:
    Redding, California
    Neil....It's still about as close as you can get. I agree that inches is a far better indicator than that old % junk.... Dan
     
  5. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

    Joined:
    Jan 29, 1998
    Messages:
    7,119
    Location:
    Naperville, IL
    Neil,

    I'm a little slow today, as you know, but I'd like to ask for clarifications on your 3 points. Please excuse me if you've answered these questions before, but I've never read comments from you on this topic. Maybe I should get your book. Is it out yet? I haven't heard.

    First I'd like to say that I thought the over all concept of percent high has to do with the vertical line we draw when we put a + sign on the cardboard and shoot directly at the crossing point of the two lines. The percentage number is the number of pellets above that line divided by the total number of pellets. For example, if you have 1000 pellets and 750 of them are above the line, then you're at .75 which is 75% or 75/25.

    Now for your 3 points:

    1. Patterns would have to be even. They aren't; they are hot in the center.

    So if they're hot in the center and the center is high, the % measurement biases the number because more of the hot center is above the line than below. Have I got this correct?


    2. Patterns would have to be square. They aren't, they are roughly circular. (Like this)


    [​IMG]


    Why does a circular pattern screw up the percent number? For the same reason a hot core screws it up? Seems like less of an issue because that's just the way patterns are. Everybody knows that so in our brains we dismiss the detail but that doesn't make it any less real. Have I got this?

    3. Gravity would have to give a mulligan to shot. It doesn't.

    But if the general trajectory of the shot is upwards, it's plausible that the further you move away from the gun the higher the pattern will become. That seems to be an assumption that is reasonable on a gun with a rib that clearly slopes downwards as you go towards the bead end of a barrel as in this here gun.


    [​IMG]


    Just wonderin'. Thanks Neil. And by the way, I'm sticking to inches because it's a lot easier to measure.
     
  6. 1166

    1166 Member

    Joined:
    Feb 5, 2009
    Messages:
    124
    Neil where are you measuring.from on the patern top, centre or bottom?
     
  7. Dr.Longshot

    Dr.Longshot Banned Banned

    Joined:
    Jan 29, 1998
    Messages:
    5,722
    Yawn, Yawn Neil, Neil you don't know if the center is hot, and you don't know if he shot it at 38-40 yards, so stick w/your graphs.

    I shoot guns w/100-120 % high poi and I know my inches to % after shooting and patterning for 44+ Years, I use percent for expierenced shooters and inches for newbies.

    And I shoot off a rest at 38 yards w/my sight picture, at a 3 inch circle

    Gary Bryant
    Dr.longshot
     
  8. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Joe, I am surprised you haven't heard my screed on the subject of "percent high." It was pretty much "my thing" until I realized that trapshooting would be better served by me constantly going off on people who claim to be able to read target breaks so that's my "area of concentration" now.


    First, look at Dan's numbers, which are, I think, straight party line down to the last tittle and jot.They are clear enough - if 4/5 of the pellets in your pattern are above the point-of-aim, you have an 80/20 gun and can count yourself among the top shooters at your club for sure - so few can handle even 70/30! And that's 9 inches high and if you are good enough to shoot 80/20 then your gun must shoot 9 inches high, QED, what's the question?

    The questions arise when you look at a real pattern and find that not a word of that table Dan gave us checks out. The last time I did this no one understood what I was getting at at all, so I'm going to go so slow you will be looking for the accelerator before we are 15 minutes into it.

    Here's a real pattern, full choke, 40 yards.

    [​IMG]

    We will start with that red horizontal line apparently right in the middle of the pattern. And it is in the middle; half the (counted) pellets are above it, half under. So if the intersection of the red line and the fat vertical Magic Marker ® trace had been my point-of-aim, this would be one of those hopeless 50/50 patterns everyone warned you about. That's pretty clear, isn't it? Shoot at something; get half the charge above it, half below; call it 50/50.

    Referring back to the real pattern, look at the horizontal black line below the red one, the labeled "60." In this case, a counted 6/10 of the pellets are above that line, 4/10 are below. So if our point of aim had been at the intersection of that line and the vertical Magic Marker trace, this gun would be called "A 60/40 shooter."

    And so on, each labeled horizontal line laying out a POI which result in the appropriate designation, 70/30, 80/20 and so on.

    The white line is a chord of the pattern circle, and is 12 inches below the pattern center. Look back at Dan's table again, and you will that that the matchup is no good at all. Imagine shooting at the intersection of that white line and the Magic Marker one.The 90/10 pattern-line is not not centered in the white one, it's at least a third of the way closer to the pattern center. A 90/10 pattern is not centered 12 inches above the POA as the calculations claim, it's more like 8 or 9 inches! And the same with all the rest. They are not a nice, even, three-inches apart, They start about two inches apart and just sort of jiggle around there, widening a bit as you move to more extreme values.

    The reasons are:

    1. The hot center means that when you start to move the pattern up the percentage number changes a lot. Not ten percent every three inches, of course, but maybe as much as two inches.
    But the pattern thins out, so the same distance change moves fewer and fewer pellets above the POA

    2. and the fact that the pattern narrows (and so has fewer pellets) just makes it worse.

    When you are done and have a 90/10 pattern at 8 or 9 inches high, there are hardly any pellets to move and so the shift to 90/10 to 100% covers about six inches and really makes hardly any difference at all pellet-count-wise. But of course it makes a huge difference in where the center of the pattern is. This is just another aspect at which the "percent high" paradigm totally breaks down.

    That's why the numbers - say 6 or 8 or 2 inches high - tells the whole story with perfect accuracy (and you don't even have to count the pellets.) And that's why percentage is just for people like to guess, generally don't test anything, and just like the aura of expertise that "shooting a 75/25 gun" gives them at the club. It's more appealing to them than knowing where the gun actually shoots.

    Neil
     
  9. GW22

    GW22 Active Member

    Joined:
    Feb 19, 2008
    Messages:
    6,246
    Great post, Neil. Very interesting info for those with intellectual curiosity and respect for techinical accuracy. Thank you.

    -Gary
     
  10. mich746

    mich746 Member

    Joined:
    May 2, 2013
    Messages:
    318
    Neil, you know I'm a fan and a believer of your POI paper. I find it odd that a shooter will pay big bucks for there gun and not POI test it at 13 yards. They put so much effort in other aspects of the game but fail to POI there gun. That should be chapter one, page one. Who would buy a deer rifle and not scope it in before going hunting?

    That being said, I'm a new shooter and need a little help so I'm going with a 70/40 pattern.
    Mich
     
  11. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    You will do fine, Mich. As is happens, I've just developed some 70/40 choke tubes and put them on the market - but you are going to have to get in line behind the big dogs - these are going to go fast! That extra 10% of pellets really puts breaks on the scorecard!

    Neil
     
  12. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Dr. L, your point about distance is a good one.

    When you talk about inches you say "Five inches high at 34 yards" or "at 40 yards" or whatever.

    Your first clue that "%-high" users are bluffing is that they don't specify the distance. And that figure changes more - or sometimes less, I guess - than the "inch" one as distance changes.

    I suppose it's a matter of judgement, but when you say

    "I use percent for experienced shooters and inches for newbies."

    I really think that's, in general, backwards. It's the newbies who fall for percentages and the whole ballistical charade that goes with it. Experienced shooters just walk away.

    Neil
     
  13. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

    Joined:
    Jan 29, 1998
    Messages:
    7,119
    Location:
    Naperville, IL
    Thanks Neil. I read your post through carefully and I get it. The chart equating inches high to pattern percentage is wrong. It just doesn't reflect reality. Because as you move from the center of the pattern the percentages change at different distances on the cardboard - 10, 20, 30...

    One final question: what if the pattern density was even? Then the circular nature of patterns would present problems - "there are hardly any pellets to move and so the shift to 90/10 to 100% covers about six inches". I see that too.

    My gun shoots an inch high at 12 yards. Clear enough. Simple and easy to measure point to point.

    The bottom row shows what I shoot. Top row was a check for what I thought I needed for yardage. That's 3 inches high. After moving back to 45 yards I saw that very few pellets even hit the cardboard - 133 in fact, so I moved my pattern back down and have been happy with the results. By the way, this is with 1-1/8 oz of steel #6 shot through a extra full fixed choke - .040" constriction. Smokes them bios.


    [​IMG]
     
  14. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Joe, we really don't have to speculate how percentages would work if patterns were even since they aren't. None of them.

    There's a theory that cylinder-chokes throw even patterns. They don't. Using distances that let you compare things - say shooting both full-choke patterns and cylinder-choke patterns at distances where the diameter of 75% of the shot is about 27 inches (like a full choke at 40 yards), the patterns are indistinguishable. They are generally somewhere between 1.5 and 2 times as dense (on a pellets-per-square-inch basis) in the inner 20-inch circle as in the outer 20-to-30-inch annulus.

    And as you understand, that ensures any system that depends on equal distance in pattern-percentages just can't work. That's no problem, of course, since there's no use for such a system anyway. Once you know "where" it shoots you know everything.

    It's kind of sad to see how dependent shooters have become on "percentages," thinking that's a ticket to understanding the game as "experienced shooters" do. Unless you talk about your gun that way, they think, you won't really know what's going on. And probably way more important, your buddies won't think you know what's going on.

    I'll be at the pattern board fiddling around and someone who thinks he might have a POI problem drives up and asks for a little help. We get all set up with a roll of white paper, a bench, a Magic Marker Magnum, a chair, and some premium light 7 1/2's. He shoots several shots and, in general, we find that it shoots a bit high and otherwise OK.

    NW: "Looks OK to me, Bob. Call it a little high and straight."

    Bob: "What's that, 70/30? 80/20?

    NW: Look at the holes. They move around a bit but on the average I'd say an inch high, sometimes a bit more. On the average only, keep that in mind. These things are not rifles.

    Bob: "70/30?"

    NW: I don't talk that way, Bob. Your gun shoots straight and a little high. That's all we know.

    (Back at the club I hear Bob telling his league-team mates that he tested his gun and it shoots 70/30.)

    People somehow feel they just have to translate a solid piece of knowledge into nonsense. I can't understand it.

    Neil
     
  15. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

    Joined:
    Jan 29, 1998
    Messages:
    7,119
    Location:
    Naperville, IL
    Neil,

    Since the distribution of pellets is indistinguishable across chokes; a full choke and a cylinder choke both have hot cores, we do have somewhat of a standard with the percentage thing, albeit cruddy. It's equally poor. Since it's poor across the range, it washes out. The crud washes out in people's minds. Psych 343?

    Heh.
     
  16. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Except that it's "crud washes people's minds out," I think, Joe.

    That's why it's important to get stuff like this right. Careless thinking makes it impossible to see the simplest things - and what could be more simple, or important, than where your gun shoots? - and makes shooters fall victim to the most transparent scams.

    [​IMG]

    Neil
     
  17. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

    Joined:
    Jan 29, 1998
    Messages:
    7,119
    Location:
    Naperville, IL
    Yes, I think it is important too, at least for me...


    [​IMG]
     
  18. hmb

    hmb Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    9,411
    Rubbish. HMB
     
  19. joe kuhn

    joe kuhn Furry Lives Matter TS Supporters

    Joined:
    Jan 29, 1998
    Messages:
    7,119
    Location:
    Naperville, IL
    Neat. I want one of those.

    HMB - Are you shooting 60/40 or 70/30?
     
  20. hmb

    hmb Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    9,411
    I don't want to know. I pull the trigger and the targets break. Neil taught me how to read the breaks and I make adjustments as needed. HMB
     
Search tags for this page

poi full form defination