Much Ado About Ribs
An earlier installment of “From the Bench” explored Barrel Regulation in double guns at length and illuminated the process of pulling twin tubes together and securing them in place. Central to the architecture of the multi-barreled gun are the ribs situated and soldered between the barrels. In common reference to shotgun barrels, however, the “top rib” is typically discussed as a fixture running the length of the barrels that serves, directly or indirectly, to help align the shooter’s eye with the target. Variations in shape, finish, and height of these ribs are a frequent topic of misinformation or confusion among shooters. What follows is an attempt to demystify ribs and their utility.
The “rib” upon which the bead sits, and along the length of which the shooter looks when the gun is mounted, lays between side-by-side barrels, and atop the upper barrel on a stacked-barreled gun. From a nomenclature standpoint, ribs come in two primary “shapes” that describe their longitudinal aspect. A “flat rib” is just that; from breech to muzzle, the rib is flat along its length, meaning that a yardstick could be laid atop it on edge and the entirety of the rib would be in contact with it. A “swamped rib” or “game rib” follows the barrel contour, beginning at the breech and bending down as the barrels reduce in outside diameter only to rise back up at the muzzles. Were the same yardstick laid on the swamped rib, only the few inches at the breech and the few inches at the muzzle would make contact. In effect, the swamped rib terminates at the muzzles of the side-by-side gun at a point slightly higher than the portion of the rib at the breech, allowing the side-by-shooter a slightly high point of impact above or ahead of the bird. In this case, the visual effect allows more of the bird or the target to be seen over the mass of the barrels. To complicate matters a bit, some modern sporting guns have high or raised ribs, mid-height or medium ribs (slightly less than the high rib but still above the top of the receiver), vented ribs (high or medium, but raised in posts above the barrels, or adjustable ribs (moveable up and down on a ramp system). These latter few are generally flat ribs that are positioned above the top barrel in an O/U gun, and, in the case of an adjustable rib, move as a unit, with the longitudinal “flat” remaining a constant, but that angle of orientation between rib and barrel being adjustable. The adjustment allows the shooter to manipulate point of impact relative to the sight picture, enabling a higher point of impact on rising targets, and also clears the line of sight above the barrels for a cleaner view of the target. To muddy the waters completely, a raised rib needs to work in concert with stock dimensions to ensure the desired effect, as stock, head position, and rib height all work in concert to deliver the desired point of impact. Note that a vented rib theoretically creates more surface area, ostensibly for heat dissipation and clarity of sight picture, though the visual distortion caused by heated barrels can be mitigated only so much.
In cross-section, ribs are concave or flat across the top, creating either a flat or concave pillar upon which the bead sits visually. The sides of the rib in cross-section are straight or angled, creating a trapezoid or a rectangle. The top surface of the rib is file-cut in a variety of patterns, or left smooth. All of these characteristics of rib shape and finish are largely the preference of the shooter, with no definable advantage making one style better than another. The only “given” throughout rib cross-sectional configuration and finish lies in the fact that a smooth, flat, highly polished rib can reflect light into the shooter’s eye at certain angles, impairing the shooter’s vision. The concave rib reflects light in and away, while the file-cut rib breaks up reflection. If flat and smooth, the rib should be matted to eliminate reflection.
Beads are yet another feature of the rib, typically screwed into a threaded hole at the muzzle end of the rib. Most are brass, steel, ivory, or, in modern shotguns, a housed fiber-optic post or pipe. Beads come in various sizes, but visually they should sit centered on the top of the pillar created by the rib when the gun is mounted, and they should not have a high polish that throws a reflection. Many sporting guns, and many American doubles, feature a mid-rib bead as well, which, when lined up with the bead at the muzzles, ensures that the shooter’s eye is centered on the rib left-to-right, and therefore aligned with the target.
Each of these nuances regarding rib shape, configuration, and finish is argued and defended among shotgun devotees, which is somewhat paradoxical in that shotgunners are taught from the outset that shotguns are not aimed but pointed, and that a shooter with a fitted gun and sound technique must only focus on the target, not the rib or bead. These admonitions are generally true, but even a precisely fitted gun and a practiced shooter need to join forces to reliably hit what they are together aiming at. The architectural reference that aligns shooter and gun is the rib and the front bead. In a side-by-side gun, the shooter looks over the breech and down the rib in such a manner that only the front bead is visible, oriented directly between the barrels. In the case of an over/under gun, the same holds true, but the bead will be centered and sitting on the visual pillar formed by the rib.
Any shooting instructor worth his or her salt will be quick to balk at the above statement, reminding the reader that the bead and/or rib should not be the subject of the shooter’s focus. Though true, the bead, oriented on the rib, requires a bit of focus to ensure proper orientation. Even if the gun is properly fitted to the shooter, somewhere in the process of mount and swing, the shooter must digest the bead’s orientation sufficiently to ensure that the gun is mounted properly and that the shooter’s eye is not positioned too high or too low, too far left or right, to deliver an accurate shot. With practice and proper fit, this orientation process becomes subliminal, and the shooter can, as the textbooks would say, focus nearly entirely on the target. That said, some small part of eye and brain will invariably take the bead and rib into consideration, or the shooter will never be able to achieve replicability. As Del Whitman puts it “when was the last time you rolled up to a STOP sign in your car and actively thought ‘now I have to depress the brake’? The sign triggers a physical response that is second nature, but no less necessary.” In short, rib and bead serve as a fact-check, one that assumes proper form and proper fit, but ensures that both combine to orient the gun and shooter correctly.
The exception to this rule occurs when proper form and proper fit are overlooked. During the era of mass production of guns that largely exists to this day, the flat rib (both longitudinally and laterally) coupled with the mid-rib bead have become ubiquitous. Such is the case because many if not most shotgun shooters do not shoot a fitted gun, but instead accommodate off-the-rack dimensions and alter their form to achieve success. In this process, the instinctively mounted gun likely results in a sight picture wherein the front bead is not centered, and or too much rib is visible or possibly obscured. To override these deficiencies in fit, the shooter is compelled to adjust their form, using the architecture of the rib as a guidepost. Without thinking, the shooter aligns both beads like rifle sights, and stacks the visualized pair atop a rectangular pillar which is the rib in cross-section. By orienting all of these reference points effectively, the shooter should have a replicable point of aim and impact, and should hit the target. Unfortunately, the process of shooting as described overrides proper form and technique, which must be re-taught when a gun is properly fitted.
As a final point, it might be helpful to reference Robert Churchill, who advocated for the relatively heavy but short-barreled SXS gun affixed with a “Churchill Rib”. Oft considered a marketing gimmick, the idea behind the Churchill XXV was to reduce barrel length from a standard of nearly 30” to 25”, distributing weight more evenly between the hands ostensibly to economize motion while retaining fluidity. The Churchill rib is a tall, flat, tapered rib that, according to Churchill, should appear to the shooter as a slim black line which optically, due to taper, makes the barrel seem longer than it actually is. Though conceptually this makes some sense, the degree of focus required to interpret the relative scale of the rib, and the perceived distance between breech and muzzles, would demand far too much attention from the shooter to have any practical value. But alas, opinions about ribs abound, and Churchill was a great example of a fine shooter who was wholly committed to the rib style and finish he preferred.
The Churchill Rib does, however, address the concept of rib tapering longitudinally, most commonly reducing in width from muzzles to breeches. In addition to creating an illusion of barrel length, the tapered rib ostensibly also focuses the eye more intently upon the target, making target acquisition more precise. Conversely, ribs that taper in the opposite direction were occasionally deployed to heighten the shooter’s awareness of target orientation in relation to the barrels on a side-by-side gun. Amidst all of these opinions, Del Whitman would again pose that a properly fitted gun mounted correctly should not allow the shooter any appreciable awareness of a rib’s longitudinal taper.
In the end, the ultimate truths regarding shotgun top ribs are few and simple: ribs should serve as unobtrusively as possible to orient a shooter’s eye up, down, left, and right on a gun reliably, so the gun can shoot where it is pointed, time and again. In a perfect world, the rib should orient the shooter’s eye and body in a manner that requires little or no conscious thought; when a gun fits properly, and is mounted correctly, the rib and bead should become nearly invisible when the gun is mounted and fired. Oddly, it seems we shotgunners know these truths academically, but can’t quite accept them somehow, and assume that some feat of top-rib engineering should make our eyes perceive our targets more brilliantly. And so we shotgunners continue to mess about with top ribs, inventing configurations, designs, and finishes that we hope will result in more birds, or more broken targets. We will probably keep doing so forever.
First Published in Shooting Sportsman Magazine
