The design and position of the fire-control mechanism are different in a true round-action, such as this McKay Brown (left), than in a conventional boxlock, like this Parker Bros. (Photo courtesy of Terry Allen).
Shotguns come in all shapes and sizes. Though variations in gauge, barrel length and even intended use are typically referenced to differentiate one from another (think “I had a great time shooting my long-barreled pump for Eastern Shore Canadas this season”), greater specificity is achieved by classifying shotguns by barrel configuration (e.g., side-by-side or over/under), locking mechanism (e.g., Jones underlever, sidelever) or fire-control mechanism (how and where the gun is cocked and how it is fired). Fundamentally, these latter naming conventions serve to differentiate one shotgun from another by describing the way in which a gun harnesses energy behind a hammer or striker and, upon trigger pull, delivers a strike to a primer.
Interestingly, through the evolution of the break-action shotgun in particular, terms for specific cocking and fire-control mechanisms have come to identify guns with even greater specificity. With added variation in nomenclature, shotgun enthusiasts have found themselves treading in some muddy waters; and with nuanced terminology, it becomes quite easy to misuse terms or confuse definitions. In this article we will explore the common naming conventions that differentiate cocking and fire-control mechanisms and designs, specifically where side-by-side guns are concerned. We also will highlight those terms that are regularly misused—or at the very least confused—when it comes to talking shotguns.
To begin at the beginning, it makes sense to describe how a break-action gun functions. A gun is cocked by opening or closing it, meaning that when the gun is opened or closed, springs are compressed, storingenergy under spring tension that can then be held and subsequently deployed when the trigger is pulled. Upon the trigger being pulled, a spring is allowed to pivot a hammer that strikes the primer, causing detonation. In the broadest and most common sense, side-by-side guns are generally divided by two unique structures that complete this task: the sidelock and the boxlock. These two basic variations are differentiated by the physical “looks” of the guns and where the fire-control mechanisms are mounted.
The older design, of which there are several variations, is the sidelock. The hammerless sidelock was really just an evolution of the hammergun, with the external hammers reduced in size and placed inside the structure of the gun where they could operate out of harm’s way. In a hammerless-sidelock side-by-side, the hammer, sear and intercepting sear as well as springs and other bits are mounted on a plate. The outside face of the plate is the curved metal bit behind the frame and below the toplever, and it is often the canvas for engraving. The bits mounted on the inside of the plate—and recessed into the wood of the stock by inletting—comprise the fire-control mechanism. When retaining screws are removed, the sideplate can be detached and the entire fire-control mechanism, or “lockwork,” can be examined off the gun.
A boxlock contains all the same functional parts as a sidelock, but they are, by definition, situated inside the frame, or “box.” The famous Anson & Deeley boxlock action was patented in roughly 1875 by William Anson and John Deeley of Westley Richards mainly as a strong and less-bulky alternative to the sidelock—and one requiring less-finicky inletting of the stock wood. A boxlock action features three rectangular slots cut into the water table, or “bottom,” of the action. The center slot receives the two lumps, or “underlugs,” that protrude down from the barrels, and the other two house what are known as the cocking dogs.Cocking dogs are bars of metal that work like a seesaw, with one end, or “nose,” of each sticking out of the knuckle (the rounded front of the water table) and being retained by the forend. When the gun is opened, the nose of the cocking dog goes down, forcing the opposite end of the dog to pivot up and subsequently push on the front leg of the hammer and cam the hammer back until it is retained by the sear.
Complicated in theory, perhaps, but the key difference with the boxlock is that most of the fire-control system is housed inside the frame, making for less inletting into the wood and an inherently strong system. That said, the elimination of sideplates greatly reduces the canvas available to the engraver, which is why many guns incorporate decorative sideplates that are inletted into the stock but serve no real function other than to capture roses, scroll and game scenes.
Digging a layer deeper, we commonly hear about “round-body” or “round-action” guns. This terminology is where the real confusion begins. Historically, the frame, or “action,” of a sidelock or boxlock is squared off, as is the wood of the stock where it meets the metal of the action. In hand, the square edges can be a bit uncomfortable, which is why some makers round off the hard edges of the wood and metal. Guns with softened corners are noticeably “rounded” and often lack the drop points or shields in evidence on more traditional side-by-sides. These guns should be referred to as “round-body” or “rounded-action” guns.
A round-action (top left) and a boxlock (top right) above images of the actions with their parts exposed and arrows indicating how the parts move. Note the cocking rod in the round-action versus the cocking dog in the boxlock.
Conversely, a round-action gun, such as that made famous by John Dickson & Son of Edinburgh, is a horse of a slightly different color. Most shotgun folks differentiate the round action by specifying it as a triggerplate action, meaning that the hammer, hammer spring, sears and so on are mounted on the triggerplate. This unique fire-control mechanism is indeed slim in width, enabling a gun to be narrow behind the frame. Because the frame of the gun does not need to accommodate the bulk of the fire-control mechanism, it, too, can be reduced greatly in size. Equally important, however, is the integration of linear cocking rods that replace the pivoting cocking dogs of traditional sidelocks and boxlocks. In a round-action gun—as well as in several other designs—the gun is cocked by the linear motion of two cocking rods that, when the gun is closed, move straight back through holes in the bar of the action to cock the hammers. Because space is not required to enable the pivoting action of the cocking dogs and the housing of the mechanism within the action bar, the size of the action overall can be greatly reduced. Gunmakers such as Dickson dramatically reshaped the action by removing metal, notably from the squared edges of the action. This noticeably round action was slim, comfortable in hand and dainty, all the while retaining structural integrity, as no metal needed to be removed to create slots for the cocking dogs to pivot within.
The triggerplate action mentioned above sometimes gets confused with actions like the Westley Richards Droplock. The triggerplate action discussed has the fire-control mechanism mounted on the bottom metal, or triggerplate. Over time innovative makers recognized that the entire mechanism and trigger group could be detached and removed as a unit with a simple redesign. This feature, known as a drop-out triggerplate or drop-out trigger group, is in evidence on many Italian over/unders, notably those by Perazzi. Conversely, the true “droplock” is a Westley Richards name and innovation that was patented in roughly 1897. The droplock was developed as a response to the needs of the traveling shooter. At the time of the droplock’s inception, the British Empire was expansive and British sportsmen were shooting in regions of the world far removed from the services of trained gunsmiths. Hence, Westley Richards’ gunmakers set out to create a mechanism that could be fixed easily in the field. The solution was the droplock, which took a basic boxlock fire-control mechanism and mounted each set of locks on a thin plate that was then levered into the action. A lock with a broken spring or sear could be dropped out for access to its innards or for replacement with a fully assembled backup. (Commonly an extra set of locks were ordered with a droplock gun). The ability to fix or replace parts on the fly ensured that a day’s sport would not be curtailed.
The nomenclature goes on and on. Bar-action and back-action sidelock guns are differentiated by the positioning of the mainsprings, different locking mechanisms have myriad naming conventions of their own, and so on. In short, however, there are many terms to describe the break-action side-by-side, and many of those terms are misused. Much of the differentiation in naming refers to the design and position of the cocking and fire-control mechanism, which is generally hidden out of sight within the gun. Therefore, it can be challenging to look at a gun from a few feet away and know, beyond a shadow of a doubt, whether it is a boxlock, a sidelock or even a round-action gun.
Recognizing that some of the concepts mentioned are difficult to understand without ample reference material, we recommend referring to the thorough, illustrated firearms dictionary that has been curated by Morris Hallowell of Hallowell & Co. The resource is available at hallowellco.com/abbrevia.htm.
Buy This Issue / Subscribe Now
Read our Newsletter
Stay connected to the best of wingshooting & fine guns with additional free content, special offers and promotions.
