This is a custom shop-built barrel polishing machine to speed up the laborious process. You can see the 6 inch wide sanding belt which is driven by the motor at lower right.
Here are 7 blanks (center) with breech plug threads already cut ready to be machined and 2 finished trade gun barrels on left and one English fowler barrel with flats cut on far right.
BARREL MACHINING FOR CAYWOOD BARRELS
I get a LOT of questions about barrels and who makes my barrels. In the black powder industry and to some extent, even modern firearms industry, no one in mid-level production builds their own barrels. With exceptions of course, barrel making is it's own industry and gunmakers don't make barrels and barrel makers don't make firearms. They require completely different tooling and machinery to accomplish the two different procedures.
With that being said, I do a lot of machine work on the blanks which I buy. These blanks are drilled, reamed and semi-contoured to my specifications. I use only gun barrel quality steel (1137 stress relieved high carbon steel and 8620) and machine the critical areas of the barrels to conform to my interchangeable barrel system.
I first set up my lathe to cut the breech plug threads. The hole is bored using a carbide cutter to reach the size to allow threading of the breech. Then the hole is counter sunk fairly deeply and using a tap and also a bottoming tap, the threads are cut to the front of the oversized hole. Once the threads are cut, the barrels are taken to a custom made barrel polishing machine and all round areas are polished.
Once the barrels are polished, I take them to a special custom made 5 ton press to hold the barrels securely and carefully insert the breech plugs. The breech plug must butt up to the back of the bore to insure that no fouling can reach the threads and rust them, creating a possibly dangerous situation, Once the breech plugs are fitted properly, the barrels are taken to the upright mill for cutting of the octagon flats. After the flats are cut, additional work of turning wedding bands, removing mill marks, polishing flats and stamping appropriate markings are completed.
The next step is setting up a machining fixture in the mill vise to cut the octagonal flats. This shop-built fixture has a dividing head vise (on the left) which allows positioning of the work at the 8 different angles to cut the flats. The cutter head has two carbide inserts which cut the material and leave a fairly nice finish. This is, of course, the abbreviated version of the machine work that goes into building your barrel, but it gives an idea of work necessary to build any firearm. The flats are now cut on this English fowler barrel.
This is a closer view showing the trolley (top) which rides the rails and allows the barrel fixture to travel back and forth and polish the whole barrel. Suspended from this trolley is a gear driven motor which turns the barrel counter to the direction of the sanding belt. You can see the barrel holding fixture and the far motor which are hinged to allow the swinging of the barrel into the sanding belt. It took a while to design and build this machine, but it saves a huge amount of time and when you polish as many barrels as I do, it's appreciated.