What do you think of the advantages and disadvantages of a sunken rib such as this?

Photo from here




Also, what would you think of the rib on this one?




Appreciate your replies. Thank you!


Best-
Vikram

I have heard them called Swamp Rib. The purpose, not sure. When shooting, if the gun fits right I don't see the barrels when I shoot.

One purpose is weight reduction. The French call those "plume" (feather) ribs. And there are some ribless sxs out there, the main purpose (again) being weight reduction. The Scottish maker Alexander Martin is perhaps the best-known for producing ribless doubles.

Hello Vikram,

A sunken rib is sometimes a single piece, needing no bottom rib, so there is no hidden part of the barrels between two ribs. In addition to the weight reduction where it counts most, over the weak hand and up forward, there is no chance of rust starting its destructive work in a hidden and inaccessible place.

Take a look at the current thread on blown up barrels to see how much corrosion builds up between barrels.

In my experience sunken ribs are more frequently seen on French doubles. The French have also developed an "I" beam section on the rib of the Ideal. It sort of slides between the barrels and there is no need for the clamps and wedges rigmarole used to fix conventional double ribs.

In case there is any doubt: I detest ribs because I have seen what rust can do between the barrels.

So, what are you shooting that doesn't have a rib? Few guns were ever made sans a rib of some sort.
The corrosion issue seems to be more common on guns that have a brazed rib and under rib, rather than a silver soldered rib. Might be the higher heat involved, but, I'll let others with more training pass that judgement. My 28 gauge Darne V19 has no under rib, inspite of having a raised rib, and there simply isn't much space for any corrosion to form, and, I would see it if it were to occur. There is simply a void under the barrels.
I own a few pumps that have no rib, no corrosion there, for sure, but, no caché, either.


Best,
Ted

Ted,

I am forced to use a conventionally ribbed double because there is no real alternative.

Like you say, a Darne with no bottom rib offers no place for rust to form. Some English guns, not all, had the space between the ribs tinned, but even then rust could form in some untinned parts, and I am talking from experience here after having seen many guns undergo rib relaying.

It is perplexing to see makers go to the latest high tech machines and still maintain tinware technology for the ribs.

Admittedly there is an aestehtic factor at play. Ribless doubles, SXS and OU, can look awkward without ribs. Well, that can be fixed without recourse to the ironmongery of ribs. As for the pointing aid, (for game guns, not target work) the eye can be fooled into perceiving a whole rib even when there is only a short rib over the chambers and a short bridge at the muzzle, that is how the first Boss OUs did it, and it worked.

I think swamped ribs make the front sight seem to "float." I shoot them well for some reason.

One of mine,
Looks ODD, shoots GREAT
12 gauge 65mm chambers

Vikram...

A gent I know inquired to Gardone about a beretta similar to your photo...they identified the gun as a 1951 409bis. They called the rib, same as yours, as a "St. Etienne".

Ted, more common on OU's than on sxs, but surely you've seen Marlin 90's and Remington 32's with no midrib between the barrels. (Krieghoffs also, copying the Model 32 design.) The Alex Martin ribless used a similar system on a sxs: Joined at the back end, joined at the muzzle (with a very short "rib" and front sight), otherwise open in between. Works quite well in both cases.

And the Baby Bretton

http://www.gunauction.com/search/displayitem.cfm?itemnum=7926720

Thanks for making my point, Larry. I've actually handled a Martin ribless, but, I'll leave the model 90s for you. BTW, you forgot the most common one-The Ruger Red Label. The center ribs on that one are purely decorative, and pop right off.
I suppose I have to let a few of your senior moments slide, however. At any rate, a happy New Year to you and your's, Larry.

Best,
Ted

Thank you all for your inputs. Are there any perceived or real disadvantages to the rib or lack of it as shown in the second photo?

Best-
Vikram

Vikram,

The advantages I have determined from personal use of borrowed sunken rib doubles are a forward light feel and no place for rust to accumulate unseen. It is so easy to run an oild rag in the space between barrels of a gun with no botto rib, or a single suken rib.

I have also used several ribless over unders and they too have the same advantages. So far I have not come across a totally ribless side by side. It would be nice to heft and shoot a few shots with an Alex Martin someday.

Ted, you must have had too much New Year's cheer and forgot to read your own post--the part about "few guns" being ribless. So you turn around and point out that the Red Label is (or can be) yet another example--along with all the Rem 32's/Krieghoffs, many of the Marlin 90's, etc. Admittedly, far less common in sxs . . . but I guess those hundreds of thousands of ribless guns = "few" over there in Minnesota. Hey, it's been cold . . . guess you haven't been drinking your daily antifreeze to keep the brain cells working. My point is that "few" ain't nearly as few as your post stated--but glad you provided yet another example to agree with me--and disagree with yourself. Here's to less confusion in 2014.

You 'sorta said it all right there Larry. Since it appears you got lost in the topic, and, like usual, forgot where it all began, how many O/Us have you seen with a swamped rib?

We have perhaps five or six examples of guns made without a true middle rib, all but one being O/Us, and you call that thousands? They may have made that many of them, but, there clearly weren't thousands of ribless gun designs.

Make a note of it.


Best,
Ted

I think it's called ol'timers

Teddy you better stick to talking about something you know something about...like Moss'eburg pump guns.

Apologies for going slightly OT...I thought this was referred to as a "feather" or "plume" because of the shape of the transition piece with doll's head (don't know the technical name) and the engraving thereon:



As to the OP, I think Shotgunlover makes a case for less places for rust to hide. My Ideal 314 16 ga pictured above comes in at 5lb 14, and it is lively in the hands. So weight reduction can also be a factor. It also looks cool to me, though only when admiring it, as I don't see it when shooting.

muzzle lite is great for cottontails!

Just as a side note a sunken or ribless gun does not necessarily have to be muzzle light. the barrels themselves can be built heavier, longer or both & even a muzzle heavy ribless gun would be no problem to achieve. I have not handles a Marlin 90 in some time, but as I recall I would not call one of those particularly muzzle light.
The term "FEW" is most often used in a relative manner. When one compares the number of makes/models of sunken rib SxS, Ribless SxS or ribless O/U to those bearing full ribs then in my opinion they are rare indeed. All the models of ribless designs which have been named here I could count on my fingers. How many hands you reckon it would take to get enough fingers to count those having full ribs??? Its quite unusual for me, but this time I have to agree with Ted.

Then there are the often maligned Ithaca Flues swamp rib guns.