Guncraft

    It’s not especially rare to find older British or European shotguns with pristine, utterly original barrels that nonetheless have thinner walls than their apparent condition should dictate.
    Conventional wisdom posits that this often resulted from gunmakers striking barrels extra thin to either reduce a gun’s overall weight or influence and improve its balance—or its “handling,” more precisely put.
    While this was sometimes the case, Russell Wilkin, technical director of gunmaking at London’s Holland & Holland, offers a more prosaic explanation: “Poor tube-making,” he said. “Someone in the maker’s barrel shop did not pick up on inherent flaws in the tubes before starting work.”
    In part, it was this problem that led Holland & Holland to bring all of its tube- and barrelmaking operations in-house when engineering conglomerate Vickers-Armstrongs Ltd. stopped supplying tubes to the gun trade in the early 1960s. Holland’s faced the choice of either finding another supplier or making its own.
    “The tubes Vickers had been making were just awful,” Wilkin recalled. “Typical problems were eccentricity, dreadful exterior shape and very poor dimension tolerances brought about by the machine operator only working to the correct diameters at the points along the tubes that he knew the ‘inspector’ would check. Our barrelmakers had to spend an entire day—a hard slog—just ‘stripping and striking.’”
    Rather than face the vagaries of another bought-in product, Holland’s purchased the Vickers machinery in 1965, brought it to its Harrow Road factory, and since has made its own tubes in its machine room, thus gaining full control over the entire barrel-manufacturing cycle. In September/October’s Guncraft—“The Case for Concentricity”—I discussed the steps H&H uses to ensure near-perfect concentricity in its tube-making: a rigorously monitored, multi-step operation that combines craft skills with aerospace-age machining technology.
    I left off in the barrel shop on the factory’s second floor, where I watched as three craftsmen—foreman Mike Birch, Warwick Dauncey and George Woodruff—turn tubes into barrels. In contrast to the machine room, Holland’s barrel shop remains one of the factory’s most traditional.
    It takes a minimum of four or five years to train good barrelmakers, Wilkin said—“forever” in today’s job environment—and their skills only improve with seasoning. Holland’s barrelmakers work to a set of prescribed dimensions for wall thickness and outside diameter when building barrels, but their craft is founded on hand-skills requisite for wielding a bevy of specialized files, and with eyes trained and tuned by experience to catching the tiniest imperfections or variations from form. With them, Birch, Woodruff and Dauncey produce barrels that to the casual observer appear virtually identical to those from a century ago.
    Yet there have been changes—some obvious, some subtle—and not only with the composition of barrel steel, which has improved dramatically since World War I. One obvious change is the use of only chopper-lump tubes—or demiblock tubes, in the case of the over/under. Dovetail construction, associated with lower grades of guns, has disappeared from Holland production, and the modern monoblock has yet to appear at Harrow Road.
    A more subtle change has been in a typical barrel’s profile—that is, its exterior shape and wall thicknesses from breech to muzzle. The ubiquitous 12-bore side-by-side serves as example: On today’s Holland Royal, the profile is more parallel down its length than in the past—thinner at the breech, where there are immense reserves of strength, and slightly thicker about halfway up and extending to the muzzles.
    “So many old guns have had their lives shortened through the years by damage or metal removal in the critical area 12 to 24 inches down the barrels,” Wilkin explained. “One of the very first things we did in the ’60s when we brought tube-making in-house was to ‘pinch’ some metal off the breech and, in essence, move it down the tubes.”
    Whereas a typical Holland 12-bore barrel circa 1900 might have a nominal .030" wall thickness measured 15 inches from the breech face, today’s barrel would mike .0375" at the same location. This correspondingly will produce minimum wall thicknesses of .032" farther up at a barrel’s thinnest spot, rather than .028" (or thereabouts) typically seen in the past. As noted last issue, when combined with today’s tough, modern steels and Holland’s stringent emphasis on concentricity, this creates stronger barrels that are inherently more resistant to damage—and if damaged, then more safely repairable.
    “Because metal has been redistributed down the length rather than added,” Wilkin said, “overall barrel weight has not increased, nor has the weight of the gun.” Considered in isolation, metal redistribution such as this will move the balance forward—or, more accurately, increase moment of inertia (MOI). However, the redistribution effect is subtle and can also be counterbalanced elsewhere.
    “Weight added to the stock can be positioned forward toward the action or just below the butt end,” Wilkin said. “Varying the barrel length also has a much greater effect on handling than moving a few thou of material 12 inches up the barrels.”
     Though I have discussed typical barrels and nominal wall thicknesses, it is still possible for Holland’s to make thinner or thicker barrels, depending on the purpose of the gun or customer requirements. Customization is, after all, the essence of a bespoke “best” gun. For a 12-bore Royal side-by-side, for example, H&H uses three tube configurations to build barrels upon: a standard game tube, a heavier pigeon version, and tubes that dimension-wise fall between game and pigeon weights. Typically, the latter are used for “fitters-in” (replacement barrels), due to variations in the sizes of vintage actions, their breech faces and their accompanying forends.
    “If we are looking to reduce the weight of a barrel assembly or looking to match replacement barrels,” Wilkin said, “a barrelmaker will ‘strip’ material with files, then strike up, always keeping an eye on wall thickness and concentricity.” Holland’s barrelmakers can “strip & strike” down to .027" or .028" if requested, and they can even go to .025" for 12-bore two-inch guns.
    “I should emphasize that stripping of a tube to produce desired variations to the form must take place at the start of the process before the tubes are joined together,” Wilkin said. “Once joined, the full circumference of the tubes becomes inaccessible.”
    After the tubes have been struck (and stripped, if necessary) to perfect form and concentricity, the barrelmakers braze (hard-solder) them together at the breech lumps in a muffle furnace at 600° C with a cupro/silver eutectic alloy to ensure a very precise melting point, which creates the basic barrel assembly. The forend loop is then hand-fitted and brazed in place, the tubes cleaned off, and the breech ends hand-filed to blend with the profile of the barrels. After blending, the barrels’ breech rings will be just undersized of the face of the action, leaving enough metal surplus on the latter for an actioner to later file and shape the gun’s fences.
    During my visit, I watched Birch and Woodruff  “smoking in” ribs in preparation for soft-soldering—or “tinning”—them on. First they blacked a rib with smoke from a paraffin lamp, and then they fitted the rib to the barrels, examining it carefully upon lifting for any bright “high spots” revealed by excessive metal-to-metal contact during the dry fitting. High spots were then dutifully filed off. It is a process repeated as often as needed to perfect the junction between rib and barrels, as well as to perfect their sweep and taper—and the overall aesthetic relationship between components when joined. It is a job that clearly cannot be rushed: “We spend a lot of time filing the ribs,” Birch said. “Maybe 14 to 15 hours, all done by eye and hand.”
    Holland’s still uses the time-tested method of soft-soldering to join ribs to barrels. The undersides of the ribs and the corresponding surfaces of the tubes where they will be secured are first painted with an aggressive flux and tin mixture, then heated to tin-coat all of the components, and then thoroughly cleaned. The ribs are attached and wired on at four or five locations down the tubes, with a small wedge placed under each twist of wire atop the ribs to help compress bearing edges together. A clip at the muzzles keeps the tubes straight and parallel. The barrel assembly is then placed on parallel steadies to lend support as pure pine rosin flux is dribbled into the crevices between rib and barrels as the barrelmaker plays a 240° C “soft” flame from a gas torch over the assembly, moving it constantly to keep the tin from burning. The rosin melts (it smells like turpentine), causing the tin to run, thereby creating a seal that will withstand decades of hard shooting.
    Nowadays there are any number of ways to lay ribs on double guns, including silver-soldering and even using lasers, but the low temperatures involved in Holland’s traditional process not only prevent any distortion between rib and barrels but also are benign enough to obviate any heat-related compositional changes that might weaken the steel. Should a rib eventually spring through repeated shock, it can be easily re-laid, and the tinning used protects the barrel against rust and corrosion should any water leach in past a lifted rib.
    As I watched the barrelmakers ply their trade, I did notice missing from the space between the barrels any indication of “packing pieces”—small supports barrelmakers traditionally placed at intervals between the tubes to keep the axes of the barrels in the same relative position and to complement the strength of the brazing at the breech. I asked Wilkin about their absence.
    “You don’t need them if you know what you are doing,” he said. “At Holland’s we set great store in machining the mating faces of the tubes to give the correct breech centers and to bring the barrel muzzles to a touch. By careful wiring and the use of wedges, we hold the barrels true in tinning.
    “Many old guns show marks in their bores where they have been lapped, revealing packing-piece ‘hollows’ where the packing expanded from the heat of friction during lapping, creating a slight bump, which was lapped off. When the metal contracted on cooling, it would leave a witness in the bore—much like shaving a pimple off. Without packing pieces, this does not become a potential problem.”
    With the ribs on, the barrel set is then painstakingly cleaned of burnt rosin and excess tin with files shaped to fit crevices, and then the barrels are papered down. The chokes—at this point still at .040" nominal Full constriction—are then reamed to the customer’s nominal specifications. The bores are lapped, and then mirror polished on an old lathe with a revolving rod tipped with a Turk’s head of emery-paper strips. The processes remove only a thou or two from the bore, but the task is time-consuming—taking about five hours.
    The ultimate goal is, in Wilkin’s words, for each barrel to be “absolutely true.” These steps—the final lapping and polish—“true up” the bore. “Passing the reamer down the bore to modify the choke can leave superficial blemishes,” Wilkin said. “Final truing up removes any slight imperfections or tiny variations in bore diameters.
    “I doubt this has any effect on the shooting of the gun, but it is nice to look up a pair of barrels and see a lovely shape up the outside and a bright true bore—it just reeks of quality and attention to detail and skill, and everything that goes with it.”
     Aesthetics aside, Holland’s emphasis on form—being graceful and “true” in every respect—implies underlying functional perfection: barrels that are absolutely straight; convergence angles that are properly machined; chambers, forcing cones and chokes that are properly reamed and polished and utterly concentric to the axis of the bore. It will take Holland’s barrelmakers more than 60 hours of skilled guncraft per set to achieve this. The product of those 60 hours will last the lucky owner—assuming proper care—beyond his own lifetime.
    At this point the barrelmaker’s tasks are almost finished. Barrels are sent back downstairs for the breechblock to be machined for barrel lumps and extractor beds, then they’re issued to the action shop for jointing in, then they’re chambered, and then they’re sent to proof.
    When the gun is mechanically complete, the barrels will be sent back from the finishing shop to the barrel shop for a final polishing with 1000-grit emery paper prior to blacking. Steven Cranston—Holland’s long-serving in-house barrel regulator— also will pattern and regulate the chokes at the firm’s Northwood Range and Shooting Grounds. Holland’s choke design and Cranston’s magic regulating them—the latter some of the most specialized and arcane skills in guncraft—will be subjects for next issue.