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THE TRUTH ABOUT ADJUSTABLE RIBS

Discussion in 'Uncategorized Threads' started by Trap2, Nov 17, 2006.

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  1. Trap2

    Trap2 Well-Known Member

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    There seems to be much confusion regarding just what purpose an adjustable rib has on a guns POI. Many believe that if you adjust ONLY the rib up or down, you can change the guns POI. This simply is not true. Here is how it really works. If you mount a gun with an adjustable rib and the beads line up in a "figure 8" for you and you pattern it at, say 13 yards, lets say it shoots 2" high. Now you adjust the front of the rib a couple of notches lower, remount the gun, and look down the rib. You will notice the front bead is gone, and you are not able to "figure 8" the beads properly. Don't change anything else, and just shoot the gun mounted as it is, with your cheek pressed to the comb as you normally do, at the pattern board, just as you did before. You will notice the pattern HAS NOT changed a bit. It is still 2" high at 13 yards. Now, RAISE THE COMB enough so that you can comfortably "figure 8" the beads again by sighting down the rib with your cheek in its normal position on the comb. Shoot another pattern and you will notice your pattern is NOW significantly higher than it was before you raised the comb. You need to raise or lower the comb to get your desired POI, and THEN ADJUST THE RIB to get your desired sight picture. I hope this helps clear up some of the mystery that surrounds adjustable ribs when it comes to POI.......Dan Thome (Trap2)
     
  2. JBrooks

    JBrooks TS Member

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    That is all true, Dan.
     
  3. hmb

    hmb Well-Known Member

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    Dan you have it backwards. On a weapon you adjust the sights to change the point of impact. Then you adjust the comb to get the desired sight picture. HMB
     
  4. Charles L. Schmidt

    Charles L. Schmidt TS Member

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    I have to disagree with you HMB. “Weapon?”

    Dan's explanation is pretty much spot on, except that you can't go do the same thing after only moving the rib as he suggests. Because the sight picture won’t be the same, so you can't really do the same thing.

    I prefer to move the two simultaneously. If I want my gun to shoot higher I'll lower the front of the rib and adjust the comb to provide the bead stack that I like (not that I much care really). Then if it's not high enough I'll repeat the procedure. Unless I only need to raise it slightly, in which case I'd put a little space between the beads. In other words I'd raise the comb so I could see some rib between the beads.

    Whatever you do don't get hung up on how the beads look. As long as you can see the target and repeat the gun mount exactly the same every time. cls
     
  5. djpk69

    djpk69 TS Member

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    as said earlier.......raise that rib/or lower (using extremes) 2 feet.....and what would happen?????
     
  6. Charles L. Schmidt

    Charles L. Schmidt TS Member

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    What would happen? Well if you raised the rib two feet and didn't change the comb, you'd not see any bead or anything for that matter, just the back of the rib. And if you lowered it two feet (not sure how you'd go about that) and didn't move the comb, you'd not be able to use the beads in anyway as reference to accurately point at anything.

    I understand what you are trying to point out, it just doesn't fly. cls
     
  7. snowbird trap shooter

    snowbird trap shooter TS Member

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    HMB is 100% right! Your eye is the rear sight. It is the only way to change point of impact on a muzzle loader with fixed sights. Start with a front sight thats too high and file it down until you're on target. It's worked that way for the last 500 years or so. Lower the front of the rib to make it shoot higher. Change the back of the rib to regain your figure eight. A projectile is a projectile. It dosen't matter what type of gun it comes out of.
     
  8. djpk69

    djpk69 TS Member

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    So,with an adjustable comb and rib....if you "leave" the comb alone and lower/raise the rib nothing will change ?
     
  9. Cherokee Kid

    Cherokee Kid TS Member

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    Snowbird, hmb is wrong as are you. I shoot a gun with a high, adjustible rib but with out beads so a figure 8 sight picture is of no concern to me. I adjusted the comb until my POI was where I wanted it by using a 13 yard target board. Then I adjusted the rib so that it was flat. When I mount the gun, all I see is the backend of the rib and I look right over the top of the gun. My doubles gun has a fixed rib but wit an adjustible comb. It is adjusted to the same POI using the comb hight. It also has no beads but I see the rib as a ramp. It is unimportant because the comb determines POI.
     
  10. Charles L. Schmidt

    Charles L. Schmidt TS Member

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    dkusner, I wouldn't say nothing, slight movement in POI may occur, probably not enough to record. Or it may result in you shooting it so differently that the POI does move some. But it's not the proper way to move POI, moving the comb is.

    And as all Trapshooters know, your eye is the rear sight. So that's what you move.

    Snowbird, we're not talking about muzzle loaders, rifles, or pistols. We're talking about shotguns. Churchill explained shotgun POI adjustment back in the late 1800's. It hasn't changed. cls
     
  11. Easystreet

    Easystreet Well-Known Member

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    In the initial example given by Dan, why would anyone want to LOWER the front of the rib if the gun is shooting too HIGH? This would only make it shoot higher...... once you get the comb up high enough to see it, of course.

    Remember, when making adjustments to sights, the rear sight (your eye) is moved in the direction you want the pattern to go. The front sight is moved in exactly the opposite direction to accomplish the same thing.


    Easystreet
     
  12. Trap2

    Trap2 Well-Known Member

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    Easystreet...Read my post again. Nowhere did I say to lower the front of the rib if the gun is shooting too high. I said if you lower the front of the rib and raise the comb to get your normal sight picture it will result in the gun shooting a higher POI. The results are ALWAYS going to be the same. If all you do is raise or lower the rib, your POI WILL NOT CHANGE. You MUST raise or lower the comb (in essence, the rear sight) to have any effect on POI. You can talk about it all you want and beat the theory to death, but the truth is in the patterning. I have tried to show, in terms almost everyone could understand, how the comb and adjustable rib are designed to work. To those of you that doubt my explaination, just keep shooting like you have been. For those of you that have grasped the concept, I hope it helps you in your search for the POI you are looking for and helps you break more targets......Dan Thome (Trap2)
     
  13. djpk69

    djpk69 TS Member

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    Think I've grasped it now.... much like a transit ....confusing....up is down and down is up.....but still comes back to the REAR sight.Thank GOD I got fitted and leave well enough alone !
     
  14. Easystreet

    Easystreet Well-Known Member

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    Dan,

    I already read your post carefully, thank you. I didn't say that YOU said to lower the front of the rib if the gun is shooting too high. However, that is exactly what you did in your example. My question (as I stated above) is "Why would anyone WANT to lower the front of the rib if the gun is shooting too high?"

    Also, at times in your post you referred to raising or lowering one END of the rib and other times you referred to raising or lowering the WHOLE rib. That's not the same thing and doesn't produce the same results.

    Easystreet
     
  15. Charles L. Schmidt

    Charles L. Schmidt TS Member

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    I'm gettin' dizzy...

    cls
     
  16. Kolar Dan

    Kolar Dan Member

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    The only gun I know of which will change POI by only changing the rib setting is the K-80 (not Trap Special). The adjustment on the K-80 actually put the barrel under tension, which will move the POI up or down depending on whether you increase or decrease the tension(bend the barrel if you want to call it that).
    Sonny
     
  17. 12Gagejon

    12Gagejon Member

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    The Adjustable rib is only correcting the site picture(fig 8) comb is only adjusting POI, change comb then you need to change your face on stock to get a fig 8 if you don't have a adjustable rib. I had a recoiless and it would confuse the hell out of you till I was told the above. only trouble was a recoiless never shot same place twice to much movement I guess Jon
     
  18. buzzgun

    buzzgun Member

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    Dan Thome,

    You are either a troll, or slept through geometry class. What you are saying is simply, objectively false.

    If you take your front bead off your shotgun, and replace it with a Pepsi can...and change nothing else...

    ...your POI is going to change a lot! Even though you didn't move the comb.

    Shooters use the bead like a front sight in creating a peripheral sight picture and aligning/pointing on targets. Otherwise, why have it? And if you move that front sight...and move nothing else...your POI will change.

    I'm going to take the more charitable assumption, and conclude you're a troll. You couldn't possibly be dumb enough to really believe what you're saying.
     
  19. hmb

    hmb Well-Known Member

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    Let's end this thread with this thought. You move the sight to change POI and you move the comb to get the proper gun fit. HMB
     
  20. AveragEd

    AveragEd Well-Known Member

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    I guess by posting my opinion, I'm going to be saying that the manuals that come with adjustable guns are wrong. But think about this once.

    Your eye is the rear sight; move it and you move POI - I think we all agree on that. But two sights are required for proper gun-to-target alignment, thus the purpose of a front sight on any gun. Snowbird and Buzz are on the right track. Filing (lowering) the front sight on a rifle or handgun changes (raises) the gun's POI and substituting a Pepsi can for the front sight (which would emulate raising it) also changes (lowers) the POI. In other words, movement of EITHER sight affects POI.

    Back when the Browning Plus guns came out, two of the best shooters in the state who happen to live nearby bought BT-99 Pluses. I was at the club where they were getting their guns set up and they would shoot and adjust upward, then shoot and adjust downward. They'd move the comb to get the POI they wanted, then move the rib to get their sight picture back. Then they'd be too high (or low) and adjust again. Up and down, down and up they went until it finally hit me that they were in fact double-adjusting.

    They told me I was nuts because the book said to adjust the gun the way they had been. By pointing out that the book's method hadn't been working for them, I got them set the guns too flat and then only raise the comb until the guns shot where they wanted, ignoring the vertical bead alignment for the time being. After they shot several perfect rounds with the guns adjusted that way, I asked them to move the rib to get their beads stacked again and the chipping and missing started all over. They lowered their front beads to regain that alignment and then the guns shot too high. Eventually, they found that "sweet spot" where moving both the comb and the bead down very slightly gave them the desired POI and sight picture. Lowering the comb lowered the POI slightly and lowering the bead raised it an equal amount, putting them right back where they wanted.

    In my opinion, you may not be able to find that perfect combination of comb height and vertical bead alignment and I don't think it's important enough to worry about. When I make a point of looking at my gun's beads, which isn't often, I see perhaps a quarter-inch gap between them. I don't worry about that because your brain just needs to know where the front bead is and having it a little farther away from the middle bead just might make it easier to see and cut down on any head-lifting tendencies you might have.

    All I can say is that my adjustment method has worked for me and many others who have tried it.

    Ed
     
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