[WNCRob]

I own an adjustable"high rib" combo, and shoot it quite well. I also own a Pro-rib Ljutic (fixed rib), and shoot it quite well. Both guns are dialed in for me. When I shoot handicap, I add a spacer to the comb and leave the rib alone...changing the rib back and forth is a pain, and, quite frankly, I don't look at the rib when shooting...or try not to. I find that I am shooting and enjoying the Ljutic more and more. Personally, I find the adjustable ribbed gun, for me, is a fad. A taller (Pro rib is 0.70" tall) fixed rib gun is a fine alternative,generally somewhat cheaper and more durable.

WNCRob

 

[jimrich60]

Adjustable ribs are great for "fine tuning" your POI and getting the gun to shoot exactly where you point it. In this sense, I think they are a fine addition to a target gun, and a bit more than a fad. That said, once the rib is dialed in, it ought to then be left alone, in my opinion. I think too many folks spend far too much time "tinkering" with rib adjustments (sometimes, it seems, between every round). If the POI needs to changed (likely raised) for handicap yardage, then use the comb to raise it to whatever degree necessary. Leave the rib for the original fine tuning, then lock it into place and forget it. BTW, although you should not consciously see the bead and/or rib when shooting, subconsciously, your eye (and thus brain) does in fact use the bead/rib/barrel to properly align the gun and move the "point" to place the barrel in the proper relation to the target (otherwise, you could never hit a moving target).

Jim R

 

[Jim R]

Now this is what a trap gun with an adjustable point of impact should look like, The Good old Ljutic Banana Gun

 

[ljutic73]

Just another think to mess with your head....my Ljutic has no adjustable or interchangable anything....and that's just the way I like it....

 

[SirMissalott]

Liquor is made to sell not drink!!

 

[Gary Waalkes]

Whatever you think about adjustable ribs, take a look at the resale (used) market. Sellers must seriously discount guns that do not have adjustable ribs.

 

[Bridger]

It's hardly a fad. I saw one prominent dealer at the Grand turn down a trade on an MX 14 as he said there was no market for guns without an adjustable rib. Prior to adjustable ribs and combs the shooter had to adapt to where the gun shot. Much easier to have a gun that will adjust to where you want it to shoot.

 

[crusha]

So...how long until the compulsory post from the know-nothing idiot who says that adj. ribs "don't really adjust anything" and the only way you can move your impact is by moving the comb?

 

[dustmaker]

adj. ribs "don't really adjust anything" and the only way you can move your impact is by moving the comb.

 

[BigM-Perazzi]

adj. ribs "don't really adjust anything" and the only way you can move your impact is by moving the comb.

that's two..

 

[crusha]

Sigh...I can see I'm gonna have to get out my pop-can demonstration again...you guys are 2 much.

 

[OldGoat]

Whether you believe adjustable ribs are a fad or not, clearly they are here to stay. That said, my frustration with adjusting my MX15 rib/comb during the last 3 months since I acquired it has been a trip...not a good one and it's still going on. Six years ago I bought a NIB Browning XT without adjustable rib or comb. In 4 weeks I was shooting the best scores yet. Then I bought another XT (got a great deal on a used one) with an aftermarket adjustable comb. Four weeks later I was back in business then some heart surgery interfered. Getting used to the difference in the XT stock/rib configuration compared to the MX15 has put me back to the steep part of the learning curve...and the adjustable rib/comb doesn't help. Suggestions appreciated...like Gene Hackman said in "Hoosiers"...we are getting to know each other. Best Regards, Ed

 

[jimrich60]

Setting up a gun with adjustable comb and rib seems to cause many folks a lot of problems, most of them I think, unnecessary. This is often complicated by confusing, or even contrary manufacturer manual instructions. I would recommend the following simple steps to set the comb and rib for you in a couple of easy steps. First, set the rib/bead at the neutral or middle position. Then, using the comb adjustments only, set the POI where it works best for you (whether this is 60/40 or 100/0, or whatever is not relevant, just that it allows you to obtain your best breaks. Then, since the comb adjustments are usually larger (1/16 inch height change or one spacer equals geneerally 3 inch change in POI), you can then use the rib adjustment to "fine tune" the POI (the rib movement marks are usually about 1 inch change) if needed or wanted. Forget about trying to achieve some "magic" figure 8 bead alignment, or maintaining some constant bead relationship. The only angle or relationship that matters is the angle from the rear sight/your eye, and the front bead. This determines the POI, much like in a rifle (in gross terms) Once you achieve the desired point of impact, then leave it alone and shoot. It often takes hundreds of targets to get used to a particular setting, gun fit. So don't shoot a few targets, decide a change is needed, shoot a few more, change again, etc. This will lead only to great frustration and poor shooting in the end. Works for me, and many of those who have used the simple process.

Jim R

 

[midalake]

The front "light stick" type beads that take your attention away from what you should be looking at is a FAD!!!!

Adjustable ribs are sights.... which is important on any gun to have an adjustable sight.........



GS

 

[phirel]

This can really be a complex question depending on the type of adjustable rib and ones shooting style. Many shooters do not look at the front sight. So changing the position of something you never look at will not make any difference. For others, who use the front sight (ghost image), changing the position of the front sight can make a difference.

Not all adjustable ribs are the same. When I change the position of the rib on my K-80, the rib does not move but it bends the barrel up or down. This does change the POI.

Pat Ireland

 

[zzt]

OldGoat, there is a simple way to set up your MX-15. Do the following:

Set up in front of a pattern board at exactly 15 yards from the muzzle. Not 13. Not 16, Exactly 15 yards for an MX-15 barrel. Adjust your rib so the front is in the highest notch. Now shoot for POI, and adjust your comb so you are hitting your POA @ 15 yards. Record the amount of spacers under your comb. That is your base pack. You will never use less height than that.
Once you have done this, you can follow the instructions that came with your gun. For every notch you lower the front of the rib you must add 2mm of spacers under the comb. That combination of adjustments will move your POI 3" higher at 40 yards. Move two notches down? Add 4mm of spacers under the comb and move POI by 6" at 40 yards.

One caveat here. There is no law that says you have to start at 50/50. I really don't care about bead alignment, but I do not like looking flat down the rib. I like to see some rib, so I added an extra 2mm to my base pack. Yes, the top front notch no longer gave me 50/50, but so what. The extra 2mm in the base pack gave me 2" high at 40 yards.

Figuring out what your base pack of spaces is allows you to change your POI up or down at will, and know exactly what you will get. For your MX-15, it will be as follows:

Top front notch with base pack of spacers under the comb: 50/50, or whatever you set it up to be.

1 notch down in front + 2mm additional spacers under the comb = 3" higher POI @ 40 yards

2 notches down + 4mm additional spacers = 6" higher POI at 40 yards

3 notches + 6mm spacers = 9" @ 40

4 notches down + 8mm of spacers = 12" @ 40

5 notches + 10mm = 15" @ 40

It works the same way going back up.

These adjustments are compound. Moving the rib moves POI, and so does moving the comb. Each notch of rib changes accounts for about 1/3 the change; the 2mm of spacers accounts for the remaining 2/3.

So you can "fine tune" an adjustment by 1" by changing the rib only for a 1" change in POI @ 40 yards. Or, you can add or subtract s2mm of spacers without changing the rib for a 2" @ 40 adjustment. Or, do both together for a 3" @ 40 change.

 

[gdbabin]

This very topic came up yesterday at the gun club over some after-shoot refreshing adult beverages.



My buddies referred to changing the POI of their guns with rib adjustments.


I stated that I don't understand how adjusting a rib alone on a shotgun could physically alter its POI if everything else stayed exactly the same, i.e. comb height, gun mount contact point on shoulder, head (eye) position, etc.



Now before buzz-gun proclaims me yet another "know-nothing idiot", I'll just cop to it and fess-up now. At least to the know-nothing part--idiots never have an interest in learning. Anyone who knows me well will tell you I'm always curious to learn something new.



I stipulate that for a rib adjustment to cause a POI change, something ELSE has to change also.


I understand that the eye is effectively the rear sight on a shotgun. This seems practically universal in acceptance. If we accept that, all that's left is the front sight (muzzle) and the target.



Pat Ireland said that for those who use the front sight as a reference to shoot a moving target, changing its position can make a difference.



This makes sense to me, I think... It's the handgun/rifle paradigm as changing the height of the front sight does effect a change in POI in these firearms.



but...



If we change the height of a pistol front sight and leave the rear alone, don't we have to position the gun differently to acquire correct front-rear sight picture to get the expected result? In effect all we did is force a change how the pistol is aligned.



With shotguns there is no ideal sight picture per se (top of front even with top of rear etc). If the eye is really the virtual rear sight, I contend that any rib change can only make a difference if we change something ELSE in the equation. Gun mount, head position etc to maintain front rear bead relationships.



Changing the comb height physically moves the muzzle up or down in relation to the cheek point of physical reference by changing the vertical distance between comb and eye (rear sight).



I don't see how moving the rib changes the eye gun relationship with all else unchanged.



Please help me better understand.


Guy Babin

Know Nothing at Large

 

[zzt]

Guy, moving either the front sight or the rear sight changes POI.

Think of it this way. You shoulder your gun, aim at a target and freeze. You don't move a muscle. The I come and lower your bead by lowering the front of your adjustable rib. Now the bead is not on the target anymore. It is lower. Your POI is still the same, because you are frozen, but you are "pointing to a spot lower than where your shot will hit. So you have made the gun shoot higher. If I unfreeze you and tell you to put the bead on the target, you will have to raise the bead to do so.

Another way to think of this is using hinge or pivot points. You already believe that changing the comb changes your POI, so let's start there. Tie a string around your bead and hang it from the ceiling. Shoulder the gun and aim at a wall. Mark the spot on the wall. Now add spacers under the comb and aim again. The bead is going to be in the same place, because it is suspended from the ceiling. You shoulder the gun and aim at the spot. Everything looks the same, but it is not. By adding spacers under the comb, you lowered the rear of the barrel relative to your cheek by a proportional amount. So the barrel is now pointing higher than previously, even though your sight picture (eye, front bead, bird) is still the same.

Now reverse the scenario. Your cheek is the pivot point. You aim at the same spot. I raise the front of your rib. You have to lower the bead so it is pointing at the target. The barrel is now pointing lower than it was previously, so your POI is lower.

Any way you cut it, moving the bead or the comb affects POI. They just work in opposite directions. POI changes in the opposite direction when you move the bead, and the same direction when you change the comb. You lower the bead/rib to raise POI, and raise the comb to raise POI.

 

[gdbabin]

zzt,

Your illustrations make perfect sense.


Your analogy is probably most clear to those more acutely aware of the bird bead relationship when they pull the trigger.


While I claim I don't see my beads, rib, etc.; my brain must--at least 88% of the time. Maybe I should pay more attention....




Thanks!


Guy

 

[Gapper]

ZZT's explanation is right on. They should put the rib adjustment at the rear of the rib, with a fixed pivot at the muzzle. This way you adjust poi with the comb first; then sight picture with the rib adjustment, independent of each other. Not too many guns made this way. Much easier to dial in.