From a flat bar of soft iron, hand forged into a gun barrel; laboriously bored and rifled… in a shop long since silent, fashioned a rifle which changed the whole course of world history.
— Captain John G. W. Dillin, The Kentucky Rifle
How, since the 15th century and right up to the American Revolution, did weapon manufacturers drill a hole in an iron barrel flawlessly straight and over three feet long? And how was the hole maintained so perfectly parallel to the axis of an iron rod, that when a bullet was launched, it flew true to its target? The answer was not drilling, but boring. With a drill machine, the workpiece was held still while the material was penetrated. Whereas a boring machine moves the workpiece against the milling cutter, hence a boring mill, both hand or water driven.
The technology of shaping a gun barrel with a precise and centered hole, primitive as it was, by the 18th century, became a discipline of meticulous and time intense mastering. It had flourished to produce some of the most accurate weaponry of precision; one of the finest examples – the Kentucky long rifle. Replica testing at Colonial Williamsburg Virginia proved these rifles produced a bore to diametral tolerances within 0.0005 of an inch; all by hand! Comparable to the accuracy of today’s complex machinery, it is mind boggling. As gun experts will tell you, ‘it can’t get much better than that.’
How gunsmiths and blacksmiths ended up with a near perfect hole in a long tube of wrought iron involved the same basic principles that allowed Alexander the Great’s armorers to crank out spears and swords; heat and hammer. Add to that an ingenious twist of a rotating boring mechanism, and the result was a weapon that could hit a squirrel from a branch at 200 yards.
Two-Step Process With a Third Step if to be Rifled
Prior to the American Revolution and on into the 19th century, wrought iron was used in the barrels of muskets and rifles, whereas cast iron and brass were used for cannon; later wrought iron was used for the breech and by the 1860’s, the whole cannon. Steel (induced carbon to wrought iron in a closed furnace) and case-hardened iron (by the amount of slag in the iron) formed working parts of the gun; such as trigger and guards, springs, flint mechanisms, etc.
If only one tool was used to both make and expand the hole in the barrel, it would be less precise. The process of hand manufacturing a gun barrel before the advent of gas and electric driven machinery was basically a two-step process. Three steps if the barrel were to be rifled.
- First the barrel was fashioned from flattened wrought iron that was hammered and wrapped around a steel rod to precent the tube collapsing. When the rod was removed, the result was a hole in the center that would be smaller than the finished hole.
- Secondly, the hole was enlarged, cleansed, and polished through precise boring to fit the caliber of a particularly sized shot or bullet.
- For rifle barrel, it required the additional boring of grooves along the inside tube called ‘rifling.’ This set the bullet spinning as it was launched. This stabilized the shot to assure better accuracy.
First Step: Forging, Hammering, and Welding the Barrel Around a Rod or Mandrel
The following images are care of Colonial Williamsburg, Virginia unless otherwise indicated.
The gunsmith master and his journeyman heated a long piece of wrought iron in a forge. Wrought iron was produced by smelting pig iron and oxidizing it; subjecting it to heat and stirring it in a furnace without using charcoal – called puddling. Wrought iron has little or no carbon, and has varying amounts of slag; a larger amount of slag produces case-hardened iron. Slag are silica inclusions running through the iron somewhat like the grain in wood. The wrought iron was hammered into a long and flat rectangle called a skelp (also blank or plate) whose thickness was a little greater than the wall thickness of the finished barrel. They would flatten any number of these longitudinal single sheets to form the barrel.
A flattened wrought iron skelp (blank or plate) ready to be hammered to form a gun barrel tube.
The flattened skelp was laid on a swage block which is anvil-like, but with multiple groves for shaping and molding. Swage blocks were of cast hardened iron or steel. Once the iron reached a workable heat, it was removed and placed on an anvil.
Left: The skelp was hammered onto the molding swage, bending in the center and curving up the sides. Right: The flat iron skelp was then shaped into a tube by hammering and beating while rotating it to wrap around an inserted steel rod or mandrel. The steel bar is to keep the bore from collapsing as you hammer. Several reheats were required throughout the process, during which care was taken to keep the steel mandrel at a lower temperature than the skelp; this to prevent it from being welded in place. The iron was continuously re-heated and hammered until a long barrel was produced.
Rifle barrels were hammered into a rough octagonal shape. The look was popular and the sides were simpler to forge when working with a heavy tube. According to master gunsmith Wallace Gusler of Colonial Williamsburg, Virginia, “It doesn’t have any practical use; just style.” However, when finishing the barrel in later stages of the process, gunsmiths could only draw file long surfaces flat, necessary to remove rough forging marks, giving the rifle its highly preferred finish.
Seams were Forge welded. Left: Prior to forge welding or fusion of the edges that formed seams along a continual iron tube around the steel rod, flux was sprinkled on the seams. Flux is made of borax, iron filings, and sand. It melts over the seem to keep scale from forming. Scale is a layer of oxide on the surface that prevents the iron to bond in forge welding. Right: The barrel was heated to the fusion point. The master only has a few seconds to hammer fast and moderate in weight to fuse the two edges together. Metal is very hot and if hammered too hard, it will be too thin.
Master welder Wallace Gusler says that when forge welding, he “Judges the heat strictly by eyesight and hearing. You can hear the hissing of the metal when it is at the fusing point. At the right temperature you also get a lot of white sparks flying from the iron as you hammer.”
It took several hundred welding heats to finish folding the blank around the barrel to forge weld. Back and forth from the forge to the swage block, each time applying flux to the seams, while working from the middle towards the end of the barrel.
When the steel rod mandrel was removed, it left a rough bore, smaller than what would be the finished barrel hole. This served as a pilot for the boring process in the next step. It was this pilot hole that ensured the finished bore and barrel would remain concentric.
When finished welding, the barrel was heated to a dull red then buried in cinders so it cooled slowly – called annealing. The purpose in annealing is to reduce the internal stress in metal and soften it for further processing. The barrel was now ready for the next step; boring the hole to its proper size and cutting grooves for rifles appropriately called ‘rifling.’
Excellent display of flat wrought iron bars called skelps and steel rods called mandrels that are in various stages of the hammering process to complete a barrel tube. Care of the Frazier International History Museum in Louisville, Kentucky.
Second Step: Boring the Hole to the Desired Caliber and Cutting Grooves for Rifling
Once the barrel was annealed, the thin hole inside needed to be cleared of debris, bored, reamed, polished, and rifled (if producing a rifle). At this stage the desired caliber, size of hole to accommodate the size of shot or bullet, was achieved to near perfection. This precise process produced a quality weapon worthy of the enormous sum frontiersmen paid; a year’s wages or more.
The boring or milling process of the barrel entailed two stages using hand driven cranks that turned bits to cut and ream the desired hole within the barrel; the boring bench and the rifling bench. These will be illustrated. A third milling, the pan borer, not covered in this article, reamed a passage for the flint spark to ignite the main charge in the barrel.
The barrel is mounted in a sliding carriage which, when ready, will push the barrel onto the rotating boring bit.
Left: The barrel was first lined up with a chuck attached to the cranking mechanism rotated the chuck. Right: When the barrel was lined up, it was secured in place with the use of wooden wedges.
Left: Long boring bit was attached to the chuck. Center: The bit end was oiled with linseed oil. Right: The bit was ready to be inserted into the center hole pilot of the barrel; the bit was slightly larger than the center pilot hole left by the steel rod during forging.
The bit is turned by a heavy crank while the barrel is pushed into the bit. This is the boring process. If the bit were pushed into the barrel, it would be a drilling process. Boring was proven to be far more accurate and precise in calibration.
Several bit sizes were used; as many as twelve to fifteen rough bits. Each new bit was a little larger in diameter and longer in cutting surface than the bit before. During these heavy cuts, the bit was removed every inch or so and cleaned, oiled, and re-inserted. Master gunsmith Gusler says that he never bored a barrel without breaking at least one bit, often more. The broken bit was annealed (heated to a dull red and cooled slowly), filed down to a taper again and retemper. Between bit sizes, the barrel was removed and sighted in a window to check for straightness. All was gaged by the eye, no straightening devises were use. Any bends or crooks within the bore could be either hammered out on the anvil, or while on the carriage, pulling the barrel back and jamming it forward onto the bit carefully to take out crooks.
After the final boring bit was used, the finishing boring process began. This stage removed the slight roughness left by the boring bits. A square reamer was used; the squares doing the cutting.
A hickory backing piece is cut to size and pressed onto one flat of the square reamer that will be inserted into the bore. This reduced chattering – lowering the vibration of the cutting reamer that could leave a variable cutting edge. This boring is as fine as face powder.
Only one size of square reamer was used. After each cut, very thin slips of additional hickory were inserted under the hickory backing to deepen the cut slightly. Often parchment or paper was used. It could take from eight to ten additional paper shims and reaming to finish this process.
The hole was not appreciatively enlarged, but burnishes it to a mirror finished polish.
With the inside of the barrel finished, the master gunsmith and his journeyman or apprentice finished the outside by draw filing the files lengthwise over the hexagonal barrel to remove rough forging marks. It was a long and tedious job. For that reason, only the top five flats were filed as the bottom three lay against the wooden stock and were concealed from view. The muzzle end was filed even so the hole was centered. After filing, emery was used to polish; a grayish-black mixture of corundum and magnetite used in powdered form as an abrasive for polishing.
Third Step for Rifle: Rifling Cut Grooves Inside the Barrel so the Bullet Spun for Greater Accuracy
At first, smooth bore muskets were common in the American colonies as all weapons were imported from European manufacturers. Muskets were the weapon of choice for the military and militias because it fit the tactics of the day; large scale volleying that did not require aiming.
Americans began to prefer rifles by the early 1700’s when the first gunsmiths who emigrated to America did so from the German speaking regions of Europe. As such, they brought their art of ‘rifling.’ The Germans had a long history of manufacturing crossbows that spun their bolts in flight, discovering they had a better chance of hitting the target. Augustus Kotter of Nuremberg, in 1520, is credited for developing the first spiral bored rifle that spun the bullet to stabilize it for better accuracy.
American colonials in the interior and along the frontier, those who still relied on hunting for the majority of their meat, preferred the rifle over the musket because of its accuracy. Farmers in the more developed coastal colonial regions got their meat from livestock; therefore there was little need for a weapon. The family hand-me-down musket that was fired once every decade or so was just fine whenever the monthly militia meetings occurred; which was mainly an excuse to end the day at the pub.
Therefore, early American gunsmiths found themselves reboring and repairing ancient relics. And when it came to manufacturing a weapon, they were exclusively rifles for customers on demand. Rifle barrels varied anywhere from 30 to 50 inches in length. This was because the length of the barrel depended on the height of the person for whom it was made. When the finished rifle was stood up with the stock’s butt on the ground, the muzzle, or mouth of the barrel, should have reached the customer’s chin; this allowed the right height to load the weapon.
The first step was to prepare the cutting or grooving tools. Left: Two steel teeth were set in an iron rod. The rod was then pinned to a chuck to the spiral guide. Right: Spiral wooden guide that turned the attached grooving teeth.
A wooden hickory shim was placed behind the teeth and oiled with linseed oil. All rifling was done from the breech to the muzzle.
As the teeth were pulled through the barrel, they were turned by the spiral wooden guide producing the same spiral pattern on the inside of the barrel. After each cut, the guide was rotated to the next position. There were seven groove positions on the spiral guide so there would be seven grooves in the rifle’s barrel when finished.
Left: After the first seven grooves were pulled through, the depth of the cutter was increased by gluing a paper or parchment shim on the back of the hickory shim. At first it was difficult to pull through, but after a few times, the paper compacted and it became easier. At that point, another shim was built up and the process was repeated. All together eight to ten paper shims were built up and pulled through. Right: Rifle grooving bench.
Finished barrel grooves cut in barrel as seen from muzzle.
For a bullet to be fired, the gunsmith closed up the back or breech end the barrel. An iron breech plug was forged and hammered. This extension was called a tang. It was sized to fit inside the barrel. The master would eventually thread both the barrel and plug to make a firm attachment that allowed the plug to be removed when necessary.
Left: The breech of the barrel was threaded. Six bolt threads were cut which made the breech plug about a half inch long. Center: Threaded breech. Good strong threads were needed in the breech because the breech plug was the only thing between the shooter and the powder charge. Right: The breech plug was threaded with a screw plate; forged longer than necessary and tapered to make it easier to start the screw plate. The excess was then sawed off.
Left: With five flats finished on the barrel, the tang (breech plug) was lined up with the top flat. Right: A touchhole through which a charge of black powder was ignited was drilled at the breech. Note the proximity to the tang. The barrel was now complete and needed to proofed or tested.
To proof a barrel, it was loaded with four times the normal amount of powder along with a patch and ball. The barrel had yet to be mounted onto a stock as this much powder would produce enough recoil to break the stock, or perhaps even the tester’s shoulder. Worse case scenario – the explosion could rip through a weakness in the barrel and shatter the tester with metal shards. Often the barrel was secured to a thick slab of wood and staked to the ground then fired by a lit trail of powder. The barrel would be checked for cracks and swells.
It would take about a week for a colonial gunsmith to forge a rifle barrel and about three hundred hours in total to complete the entire gun. The average cost of a rifle in 1776 cost upwards of 10 £ which is the equivalent to about 1,800 £ by todays standards or just over $ 22,000. With those costs in mind, no wonder colonials valued their rifles as much as their farm and dare say the furniture thrown in. And if a weapon were stolen, the victim would often travel the length of the colony and more to get it back.
CHECK OUT THIS CLASSIC 1969 VIDEO BY WALLACE GUSLER CALLED “GUNSMITH OF WILLIAMSBURG.”
In Remembrance of Gunsmith Wallace Lester Gusler (Sept. 3, 1931 – April 21, 2022)
Mr. Gusler was an incredible craftsman and master colonial gunsmith and educator. His art was among the finest. He devoted his life to forging and manufacturing by hand authentic 18th century firearms as well as the education of thousands; spending forty years as Williamsburg’s Master Gunsmith. He and his wife Ruby of 68 years were tragically killed in a car accident on April 21, 2022. Gracious lives well lived whose souls remain embraced for all eternity.
IF YOU WOULD LIKE TO READ MORE ABOUT COLONIAL GUNSMITHING, HERE ARE SOME FREEE PREVIEWS ON AMAZON
OF SIMILAR INTEREST ON REVOLUTIONARY WAR JOURNAL
RESOURCE
Duffy, Rebecca. WPAMC (Winterthur Program American Material Culture). “Materiality of a Rifee Gun: Gunsmithing at Colonial Williamsburg.” March 2017.
Frantz, John & Pencak, William. Beyond Philadelphia, The American Revolution in the Pennsylvania Hinterland. 1998: Pennsylvania State University Press, State College, PA.
Gusler, Wallace. “The Gunsmith of Williamsburg.” 1969. Youtube video.
Kerstetter, Nancy. “What Tools did Colonial Gunsmiths Use?” Gone Outdoors.
Lufkin, Brian. “The History of Boring Mills”. Dec 13 2021 Premier Equip Co.
“The Remarkable Widow Catherine Smith.” Union County Historical Society
“Rifling History.” Firearms History Technology and Development. May 11, 2010.
Smith, Robert J. Manufacturing Independence Industrial Innovation in the American Revolution. 2016: Watts, Randy. Youtube “The Real Boring Mill Story.” 2022