There are a few basic processes that are essential to making firearms:
- Forging - This is used to make the majority of iron and steel parts.
- Casting - This process is often used to make small parts, especially those of complicated shapes.
- Machining - This is a process that uses machine tools to finish parts that were made using forging and casting processes. Rifling is also made by machining processes.
- Stamping - This is a more modern technology and is used to make parts out of sheet metal, e.g. trigger guards, parts of sights etc.
- Woodworking - Used to shape stocks for firearms from raw wooden blanks. In modern days, stocks are also built of other materials, so this is no longer as important as some of the other processes above.
- Metal treatments - There are many types of metal treatments. Applying protective coatings to various components, rust proofing, heat treatment hardening of certain components etc. all fall under this category.
- Assembly - Taking all the components and putting them together to build the firearm.
- Testing - All reputable manufacturers perform testing of their products to make sure that they are reliable and can withstand normal usage. In some countries, proof testing is mandatory by law.
This is one of the older iron working processes known to man. It was used by ancient blacksmiths and the same principles apply to the present day, even if the tools used are different. Iron and steel pieces are heated to red-hot temperatures, at which point they become soft and easier to shape. The red-hot pieces are then hammered into the shape of the finished components and then cooled down. In many cases, a specially shaped die is used and the red-hot pieces are placed into the die and hammered to their final shape. One of the advantages of the forging process is that it compacts the metal and makes it stronger.
These days, we have large forging machines that can hammer out larger components, such as receivers and barrels of rifles easily.
Casting is a process where a mold of a desired shape is initially prepared, then molten metal is poured into the mold and allowed to solidify. Casting is also an ancient metalworking processes and has been used in history to make intricate shapes as well as large objects. While a cast metal part is not as strong as its forged equivalent, it is often used to make complicated shapes which would be uneconomical to make with any other technique. One more advantage of casting is that many parts may be cast at the same time.
On the flip side, cast parts may have microscopic cracks and flaws due to factors such as uneven cooling, lack of proper venting etc.
After a part is forged or cast, it is usually close to the required dimensions, but not precisely so. It may also have tiny burrs and surface imperfections on it. This is where the task of machining comes in: to size the part to the proper dimensions and polish it as needed. Machining the parts to greater precision also makes parts interchangeable. Machining is also needed to cut rifling in the barrel.
There are various machining operations: cutting, turning, drilling, polishing, grinding etc. and there are specialized machines to perform each task.
Stamping is the process of cutting and shaping parts out of sheet metal. Unlike forging, stamping is usually done to cold metal. Stamping is typically used for parts that don't take as much heavy load, for instance, a trigger guard or a magazine. With modern technological improvements, stampings can be used to also manufacture upper and lower receiver parts for some submachine guns and battle rifles.
Stamping is also used to put serial numbers on various parts of a rifle.
WoodworkingBack in the days when stocks were made of woods such as walnut, beech, ash, myrtle etc., the art of woodworking was used heavily in the gun trade. A skilled woodworker would take a block of wood and using various tools such as lathes, chisels, planers etc., would carve out gun stocks, to which the barrel and firing action were fitted. On more expensive models, craftsmen would engrave patterns, cross-hatches, inlay precious metals etc. into the stocks.
These days, stocks are made of other materials as well (e.g.) plastic, fiberglass composite, metal etc., where woodworking skills are not as important. However, some of the finest shotguns and rifles still feature wooden stocks carved by very skilled craftsmen.
Metal TreatmentsThe various metal parts of the firearm may be treated via chemical processes, to add a thin coating that prevents rust and also may be wear-resistant. Some parts may also be hardened after machining, so that they can bear the stresses of normal usage better. We studied many of these treatments earlier e.g. case hardening, bluing, parkerizing, tenifer, melonite etc.
AssemblyAfter the parts of the firearm are manufactured, they still need to be put together to make a functional firearm. The process of putting the parts together may involve tasks such as riveting, welding, gluing, tightening screw threads, lubricating etc.
After the parts are put together, the firearm needs to be tested to make sure that it is functioning accurately and reliably. In some countries, there are standard tests that are enforced by the Government and any firearm marketed in these countries is required to pass the standard tests before it can be sold. All reputable manufacturers also run various tests during various stages of the manufacturing process, to catch any problems as soon as possible.