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THE TRUTH ABOUT ADJUSTABLE RIBS

30K views 132 replies 47 participants last post by  BigM-Perazzi  
#1 ·
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)
 
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#3 ·
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 ·
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
 
#6 ·
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 ·
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.
 
#9 ·
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 ·
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 ·
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 ·
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)
 
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#13 ·
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 ·
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
 
#16 ·
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 ·
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 ·
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.
 
#20 ·
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
 
#21 ·
Ed....

Thank you for explaining it a little clearer to these non-believers than I did.

221...

My point exactley, in the K-80 adjustment, you are essentially bending the barrel to get the POI you want, are you not?. "Raise or lower the comb, BEND THE BARREL, or adjust the chokes" to change the POI.

MIA...

Let's ask Vickie at Keensites directly. Vickie, if I put a 60/40 Keensites rib on my gun and change nothing else, will it automatically shoot 60/40 or must I adjust my comb to get the proper sight picture to achieve that POI?

Along the same line, let's pose this theory to Dennis, at NCP, Bruce, at Bowen Guns, Roger Eubanks, at Eubanks ribs, etc. Will any of you care to weigh in on this subject? Does changing only the adjustable rib have any effect on POI, or must the comb be raised or lowered?

buzzgun....

You're right..I'm probably a troll. Your mind is obviously made up, so why in the world would I want to confuse you with plain facts?

Dan Thome (Trap2)
 
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#22 ·
What's not being said here? If you replaced your bead with a much taller bead and used the top for aiming, the POI will change without changing the comb. In Buzzs example, the top of the Pepsi can will lower the POI in the same way. You would change the angle your eye is looking over said bead or Pepsi can by raising or lowering the front of the gun in relation to target. Hap
 
#23 ·
Solution is at hand and Dan T. is doing it the correct way. Get a DB81, just like the one I have for sale, with a fixed rib, and adjust the comb to make it shoot where you want it to and stop swetting the rib issue. Works every time. You cant buy a better trap gun. Tom Ward
 
#25 ·
Ahahaha..........youse guys are all nutz. Point of impact never changes relative to the gun. Point of aim is what changes.

The only one that changes POI is the K-80 lower,as as stated by bending the barrel. I believe the Browning ST-100 does a similar thing.

All the rest of this crap is simply changing where you look, the projectile(s) still go to the same place relative to the gun.

(Halfmile ducks)

HM
 
#26 ·
Dan,

According to YOU, POI can only be adjusted by raising or lowering the comb. Also according to YOU, raising or lowering the rib in any way is only for the purpose of giving you the sight picture you want. It has no effect on POI (according to YOU).

OK, so using YOUR method, I'm going to go step-by-step through an adjustment process.

Let's suppose that my gun is shooting too low to suit me. So, according to you, I raise the comb to raise the POI to my desired height. OK, so far so good. EXCEPT, that now I am not seeing my Figure 8 with my beads like I was before. I am seeing waaaaay too much rib. So, in order to get back to my desired Figure 8 sight picture, I lower the front end of the rib to give me my desired Figure 8 sight picture. However, when I shoot the gun again, I find that now the POI has raised even further due to the lower front end of the rib. So the gun is now shooting TOO HIGH. So now I lower the comb again to lower the POI, but that results in not seeing the FIGURE 8 sight picture. So, using your method, I keep going back and forth, back and forth, like a dog chasing his tail.

The only way to get it adjusted properly to have BOTH the desired POI and the desired sight picture is to realize that changing EITHER the comb height or the height of the front of the rib is going to change the POI. Therefore, the correct way to raise the POI and still keep the same sight picture is to make 1/2 the POI adjustment by raising the comb and the other 1/2 of the POI adjustment by lowering the front end of the rib. That will give me the raise in POI which I wanted while keeping the same sight picture.

Easystreet
 
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