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Comb Adjustment / Ireland-Southpark method...

Discussion in 'Uncategorized Threads' started by alpine, Apr 2, 2007.

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  1. alpine

    alpine TS Member

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    Maybe if you could consistently spell "POINT" correctly.
     
  2. Neil Winston

    Neil Winston Well-Known Member

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    Sorry, Mr. K; It adds to the confusion, at least for me.

    Isn't it backwards? I'm serious.

    Neil
     
  3. gr8shooterz

    gr8shooterz TS Member

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    I agree with Neil. The comb is the site of D-F and if the barrel were A-B then as the comb adjustment went up the barrel would shoot higher. The graphic dosn't depict it that way.
     
  4. scott calhoun

    scott calhoun Well-Known Member

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    I thought it showed one setup shooting to the right and one to the left . . .

    But seriously . . . if the comb is on the right side of the pic then I believe it is correct.

    It says "C - comb adjusted up" which leads me to believe the comb is on the right.

    Scott
     
  5. Neil Winston

    Neil Winston Well-Known Member

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    Got it, Scott. It was I who had it backwards. I guess.

    Neil
     
  6. Setterman

    Setterman Well-Known Member

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    No. It's confusing without a "Point of Impact" line. The whole thing should be smaller scale indicating a 30" or so barrel and POI at 30 yards. Done that for our 4 H group on Auto cad.
     
  7. Sam (ATA Noobie)

    Sam (ATA Noobie) Member

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    Makes perfect sense to me.

    The barrel wouldn't "shoot higher" the barrel always shoots to the same place... It's just where you see that changes.

    It would be more effective on an elongated piece of paper, as the sight paths don't cross at the end of the barrel, but the main point is displayed nicely.

    As the comb goes up, you SEE lower at the same POI, which would make it appear that your barrel is shooting higher in comparison.
     
  8. Neil Winston

    Neil Winston Well-Known Member

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    Mr. K, I see what you are getting at now that I put the stock to the right.

    But still - the diagram is all wrong and that's what the problems are include:

    1) The sight on the right (E) can never be below the barrel.

    2) Lines are lines, points are points. So EF can't be the point of aim, it has to be the line of aim.

    But your idea is right, so just fix the diagram up, and add a POI, and everything will be fine.

    Neil
     
  9. Sam (ATA Noobie)

    Sam (ATA Noobie) Member

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    No hostility needed. As I said, I think you did a damn good job of explaining it.

    They do 'intersect' there, however, as Mr. Winston more eloquently put, your lines are exagurated. You couldn't see over your barrel unlss you raised your comb 3 feet!
     
  10. southpark

    southpark TS Member

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    Mark/24STR8

    While I am always ready to admit to being wrong I usually am correct before I open my mouth on this board. I do not think this time is any exception.

    Over the years I've found that there are only about a half-dozen other people who do the same before they start posting like it's as true as if it were straight from the mouth of G_d.

    I would put Neil Winston and Pat Ireland in that half-dozen, though I love to nitpick at them both.

    Moreover, Neil and Pat are both much, much, more polite than I am. On the other hand, I usually try to limit the bad time I give someone based on their own hubris. Kind of like Simon Cowell and his judging of American Idols I suppose. Since you seem honestly to be having a little conceptual trouble rather than just being a troll (I hope I'm not wrong) I'm going to walk you through why Neil sees your chart as "basically" right while many others (remember, only a handful of people on this board consistently post the right information) think you are mixed up.

    In the case above, I think you are almost there but the diagram should have been done in three separate parts to make it easier to understand.

    Let's start by imagining we have a gun that shoots 50% of the lead at target breaking distance over your point of aim and 50% under it, on average.

    Imagine your shooting eye is 5'6" off the ground and you have a target you are aiming at (your POA or Point of Aim) out in front of you 5'6" off the ground.

    You are correct that your shooting eye functions as the rear sight.

    So with a 50/50 shooting gun we have a straight line of aim that runs parallel to the ground 5'6" off the ground if our point of aim is the target described above.

    Now imagine you raise your comb one inch or any arbitrary amount.

    The part of your face holding your shooting eye is raised when you raise the comb so you are raising your shooting, or aiming, eye when you raise the comb.

    Take a moment to picture that.

    As an easy test if you are sitting at your desk at work, point your left finger with an outstretched arm at a point on a far wall with your non-aiming eye shut and your head forward as if you were shooting. WITHOUT moving your left finger or arm, slightly raise your head -- and aiming eye.

    Did you notice that your aiming eye was still focused on the target but your left finger was then left positioned underneath the point you were focused at?

    Note that we use our rear sight -- aiming/shooting eye -- in conjunction with the front sight to form a barrel/bead relationship in our peripheral vision correct (while our sharp focus is on the target)? (Hint, the answer is yes.)

    So what needs to happen for our front sight to get into a relationship with our rear sight (eye)? We simply need to raise our left finger to once again touch our target.

    While I hope you see where this is going, let's now clear some things up that maybe were left out of your diagram.

    There are going to be two straight lines we need to think about.

    First is the point of aim (POA) line that stretches from your shoooting eye to the front sight and beyond.

    The second is the POI line, or point of impact line, that stretches down the barrel, or bore, of the gun and beyond.

    The front of that POI line is in the middle of the barrel just below the front sight right? And the rear of the POI line starts right in the center of the primer right?

    Going back to our imaginary office target think about the butt stock staying on your right shoulder. You start out with a flat shooting 50/50 gun and reach out your left hand to rest just below a "target" on the far wall.

    The next points are the key to the puzzle.

    With a 50/50 shooting gun we can assume that the lines for POA and POI run parallel to one another.

    But in our example we leave the rear of the POI line stuck in our shoulder pocket right?

    Now once we raised the rear sight (eye) we had to raise the left finger to meet up with the target right?

    So now we've got a situation where the front sight was raised which raised the front of the POI line!

    Get it now? Just in case I'll finish going through it.

    We never moved the butt of the gun out of our shoulder pocket right? So that means the start of the POI line stayed pretty much where it was (the shell didn't get raised, our eye, or rear sight did).

    But we moved the front end of the POI line (the middle of the barrel at the business end of the shotgun) when we raised our front sight (our left finger in this example).

    Now what happens when you move the front of the barrel up relative to the rear? The gun shoots higher of course.

    Similarly, what if we kept everything the same at the back end; butt stock still in the shoulder pocket and eye still at the same level.

    Now let's lift the front bead up one inch but keep the bore of the barrel in the same spot.

    In our office example replace your left finger with your left thumb and reach your arm out and put that thumb under the target.

    Now place your left index finger one inch above your thumb but keep your thumb and arm in the same place. The left finger is going to block out or even be above your target right?

    What do we need to do to be able to see the target and have the front bead right under the target again?

    We lower our left arm until the left finger is just below the target and the left thumb is one inch below the target.

    What does that do? It lowers the bore of the gun and lowers the front of the POI line. Remember, our lines pivots on the rear of the POI line which is basically the same because in our example we've agreed that the buttstock stays in the shoulder so . . . it lowers our point of impact!!!

    There are numerous folks on this board who have been arguing for years that changing the bead location via adjustable ribs doesn't do anything. They are either crazy, stupid, or "C", all of the above.

    I hope these visual exercises help clear this up. Please let me know if you have any trouble following this.

    Whatever you do, don't feel bad. Not everyone was a straight A student, and that's okay.

    Conceptualizing can be very difficult and I applaud your efforts to understand all this.

    Please emial me directly, fatXXXerikcartman@yahoo.com (remove XXX) if you prefer.
     
  11. Harold

    Harold TS Member

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    Mark,

    I think what your diagram needs is another line C B' D' where B' represents a higher bead position than B and D' represents a higher POA. This would lead to a lower POI (relative to POA). This is probably the same thing Southpark said, but I didn't have the patience to read it all.
     
  12. Rollin Oswald

    Rollin Oswald Active Member

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    I tried to copy and paste a page from my book that clearly illustrates how changing the height of the eye relative to the rib affects the POI but I failed. It should have been easy but it wasn't. (Life can be so disappointing for us computer dummies.)

    For those who cannot understand the concept involving eye height and POI, you are not alone. It's a very simple concept to understand ONLY when you understand it. It is then very simple to visualize what happens when you change the position of the eye relative to the rib.

    Unfortunately, that doesn't help at all. To describe what is happening, the drawing must have a barrel with a front bead or muzzle, an eye and a target, i.e. it must represent a sight picture. Bear in mind that when the position of the eye is changed relative to the rib (raised, for example,) the muzzle must be raised to compensate and again create a sight picture - eye/muzzle/target. The sight picture is the same but the muzzle is raised to realign the eye and the front bead with the target.

    With the eye above the rib via raising the comb, the barrel is pointing upward when the eye, front bead and target are in a straight line or aligned.

    Rollin
     
  13. southpark

    southpark TS Member

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    Mark, I think it was Walt Whitman who said:

    "Strong people make just as many and as ghastly mistakes as weak people. The difference is, they admit them, laugh at them, and learn from them; and that is what makes them strong."

    Welcome to the toughguy club!

    I think at the time I wrote that regarding three charts I thought you should have separate pictures for the before and after shots. It may not be easy to draw out.

    For those still following this (probably no one but you Mark and that is why the same arguments go on over and over on this board (even the people who know better can't always explain it right) here is another way to look at it.

    take a ruler or whatever straight edge you have on your desk and close one eye and sight down the edge at a target on the far wall.

    Now lift your eye above the back edge.

    See how the front edge is now below the target?

    Now with your eye still held above, while keeping the back edge closest to your eye in the same relative spot, lift up the front end until the edge touches the target again.

    Now hold the ruler, or whatever you are using, perfectly still and lower your eye to sight down the edge again.

    See how the edge, which would represent the POI, or point of impact line, is now pointed above the target?

    That is how raising your comb works. Hopefully no one needs me to run through this in reverse.

    Now stick a post-it note a half inch above the front of the ruler and another a half inch above the rear of the ruler.

    Sight down at your target using the tops of the post-it notes. This is your POA line. Now hold the ruler still and move your eye down to the ruler and sight down it. Notice how the lines, if extended to the target, are very very close together (about a half an inch)?

    Great! We are all almost on the same page.

    Now remove the front post-it note and aim again at your target on the far wall only this time use the top of the rear post-it note and the top of the front of the ruler as your sighting plane. That is your new sighting plane with an adjustable "rib".

    Great, we're almost there!

    Now holding the ruler perfectly still, move your eye down to the ruler and sight down the ruler. That is looking down your POI, or point of impact line.

    Notice how it is pointing ABOVE your target even though your POA line was pointinig right at it?

    This is how an adjustable rib can be used to ALSO change your POI!

    Now Mark, what is great about ts.com is that in six months you will see another thread on this board with the majority of posters saying moving a rib doesn't do didly squat about moving your point of impact. And All-American shooters like Jerry Parr will laugh, like in your other thread, about the hopelesness of the folks on this board. While nice guys who know better like Pat Ireland and Neil Winston will once again politely try to explain for the umpteenth time. Meanwhile, I will just get irritated again and call them stupid.

    You can set your clock by it.

    Good luck with your shooting and I should note, that perhaps you are not stupid after all as the definition of intelligence is the ability to learn and understand. So as long as you are "getting it" now, don't worry about being mixed-up before -- you're in good company around here.

    And please don't get me wrong, I still love you guys and ts.com, but I sometimes feel like the Matt Dylan character in "Something About Mary" when he comments on the mentally challeged kids she helps. He says "I love those goofy bastards!"
     
  14. phirel

    phirel TS Member

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    The diagram is not incorrect, but it did confuse me a little and I have some questions about the labels.

    Try this for clarification. Point your finger at an object and pretend your arm is the barrel and your finger is the end of the barrel. Point your finger at something and raise your head as would be done by raising the comb, but do not move your barrel/arm. It now appears as if the barrel has moved down but it actually has not moved at all and will shoot the same place because it has not moved. But, to keep your finger (front sight) pointed at the same object, you will have to raise your barrel/arm. Raising your barrel/arm will cause the barrel to shoot higher.

    Try this. It just takes a few seconds. Remember that the only thing that will make your barrel/arm shoot higher is moving the end of the barrel up. Moving the barrel up will be required to keep your finger pointing at the same place.

    Pat Ireland
     
  15. GunDr

    GunDr Well-Known Member

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    <a href="http://photobucket.com" target="_blank">[​IMG]</a>


    The top picture shows how a majority of shooter point and break their targets. They will either be looking flat on the bbl or looking down the rib with the beads in a figure 8. What's important to remember is that the "line of sight" never changes.

    The next picture shows the comb elevated; the eye is higher. The line of sight still remains the same...a straight line. But now that the eye is higher, the muzzle needs to be raised so that it is in that line of sight. Note, that the back of the gun does not move. The moving of the muzzle up to this new line of sight, will cause the gun to shoot higher.

    The last picture is a more exaggerated rise of the eye. Again, the back of the gun never moves, the line of sight never changes, but with bringing the muzzle up to the line of sight, will cause the gun to shoot much higher.

    Using this last picture for another example, if we knew we had a gun that shot 50/50(dead center) at 40 yds, with the beads in a figure 8, raising the comb(raising the eye) to allow some space between the beads, your line of sight is still a straight line, but if you did not move the muzzle up into the line of sight, it would appear that the bead/muzzle would be low on the target, and it would pattern exactly where it would have been, if the comd/eye had never moved. So, the human nature that we are, correct this by raising the muzzle up to the line of sight. It's this movement that makes the gun shoot higher.


    After I started drawing this out, I looked again at your diagram. Your not that far off. It just had a few bugs in it. It doesn't explain the correction you need to preform.

    Now, if I'm all wrong...let me know!!

    Doug
     
  16. GunDr

    GunDr Well-Known Member

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    On your picture, you have the aiming point moving. The aiming point cannot move.

    While you show C & E moving from A, we can assume this is your eye.

    What needs to move, when C&E moves, is point B.

    Lets turn points D & F, into one point. Then you need a line from C to DF.

    The line you have drawn from E to D & F, or with the revised E to DF, will not work, because you will be too low, and cannot see the top of the rib. Your eye will line up below the top lever. The eye needs to remain above the center line of the bore.
     
  17. southpark

    southpark TS Member

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    Obviously I am relegated to second-class citizenship until I learn to post diagrams and drawings. Sheesh.
     
  18. BDodd

    BDodd TS Member

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    I'm sure glad the later posts finally got the picture right; it saved me a lot of verbosity in trying to do it myself.....breakemall....Bob Dodd
     
  19. no5shooter

    no5shooter Member

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    For what it's worth, I understood your original drawing, Mark. And I understood it was exaggerated to illustrate your point and I never considered trying to shoot a shotgun with my head below the stock. You've got the concept exactly right, whether anyone agrees or not. How did you do in that handicap after you adjusted your rib?

    GunDoc, I like your drawing too. Well done.
     
  20. southpark

    southpark TS Member

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    Mark, I have no idea on the illustration as I have not seen them before.

    If you're asking where I got the writing, or the words and ideas I used, I did not refer to any reference at all.

    I simply used explanations that could convince anyone willing to go through the steps outlined that these things function as described.

    All the thoughts and words were my original ideas except for Walt Whitman who I quoted from something I read 25 years ago -- so even that didn't have a reference I referred to in creating my explanations.

    If I've misunderstood your question I apologize.
     
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