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Modern Firearms Manufacture (Rifled Barrels (Cut Rifling - A cutting…
Modern Firearms Manufacture
Metal-Forming Operations
Forging
Hand Forging - Performed by a blacksmith who would maually shape a barrel out of steel or iron
Machine Forging - more commonly used today.
Hammer Forging - Extreme force via a large hammer strikes a negative imprint onto hot metal
Press Forging - Similar to hammer forging, the imprint of a product is stamped into metal but much slower giving greater precision
Stamping - Similar to forging but stamping is done on thin metal sheets.Typically used for thinner components
Die Casting - Permanent reusable metal casing molds are used with molten metal (typically zinc) which is injected into a hollow space in the shape of the product
Powdered Metal Technology - A type of casting that does not require the use of molten metals. Rather, powdered metal is used to fill a hollow cast, heated until the powder melts, then cooled
Investment Casting - Wax is used as a mold and is dipped in mineral slurry then sand multiple times over. Once dried, the wax is melted, creating a hollow space for molten metal to be poured in. The dried "ceramic" is chipped off
Extrusion - The use of a hydraulic press to make low loading components
Fine-Forming Operations
Milling - The use of rotating cutters at high speeds to remove material
Broaching - A cutter with multiple grooved. Used to create the spiral grooves within the barrel.
Grinding - A technique is which metal is rubbed against metal. The grinding wheel is made of material stronger than steel and can shave a large amount of material depending on the grit
Computer Numeric Control Machining - A machine that combines most processes like drilling, turning, milling into one by using computer programs. Best used for mass production of firearms
Turning - A technique in which an object is spun around its axis and the outer diameter is shaved
Electrical Discharge Machine - The use of high frquency electrical sparks to cut/burn material into complex shapes
Drilling - Used to make holes in the firearm. Most notably, the barrel
Hand Fitting - The use of a file for adjusting components
Rifled Barrels
Cut Rifling - A cutting method in which the spiral grooves are cut one at a time with the use of a cutter head There are two forms of cut rifling: broached and botton swaged in which the grooves are hammered in
Hammer Forger - A mandrel is used to create the spiral grooves within the bore
Rifling - Electrochemical Rifling is one way to etch spiral grooves in the interior of the barrel
Electrical Discharge Machining - More often used to produce dies but can also be used to create grooves in the bore
Straigtening - The use of an optical pattern's reflection on the interior of the barrel to determine how straight the bore is
Contouring / Profiling - Typically the ends of a barrel are tappered for a better overall look. The uniqueness of muzzle can aid an examiner when working on comparisons
Lapping - A type of polishing process that is done post reaming to reduce any burrs. Typically done for firearms that use soft lead bullets
Chambering and Throating - A chamber is located at the back of the bore and created to allow specific cartridges to fit the bore. The throat is located in front of the chamber and prevents any engraving forces caused by a fired bullet
Reaming - A rotary cutting tool used as a finishing touch (smoothing rough edges) on the barrel post drilling
Barrels for Muzzleloading Arms - Shotguns' barrels are typically greater in diameter compared to other firearms. If a shotgun is rifled, it is typically a polygonal rifling pattern
Deep Hole Drilling - Drilling produces the cavity within the barrel. The way in which the cavity is drilled contributed to the firearms uniqueness
Parts Fabrication
High-Stress Load Parts - These components of a firearm experience high firing pressure and an assortment of movement. Therefore, these parts are more durable
They include: the frame, receivers, slides, bolts, breechlocks and cylinders
Low-Stress Load Parts - These components are smaller and there is typically a greater quantity of them
These parts include the lockwork / lock parts, repeating mechanism components, pins, screws, springs, and the magazine
Cosmetic Finish
Electroplating - A type of protective coating by using electrodes. This technique is used on chrome or nickel that makes the metal look brighter
Anodizing - A type of protective coating used for aluminum and titanium. The protective coating is also the results from the use of electric currents and controlled oxidized surface
Bluing - A type of coating that results in a blue or black color helps protect the steel metal parts. The color depends on the types of oxidizing chemical used
Assembly
Final Assembly - Different types of firearms typically need to be hand fitted one way or another
Subassembly - The process of assembling subunits together. Some of the subunits include the hammer, triggers, cylinders, bolts and slides
Final Steps
Serial Numbers - Every firearm is required to have a serial number which allows the firearm to be traced back to the manufacturer
Preparation for Delivery - After any tests are completed, residues are cleaned, the firearm is coated with a rust inhibitor and shipped in a padded container. Additional things like a manual, warning tags, stickers may also be packaged along with the firearm
Test Firing - This test uses regular ammunition and tests whether or not the firearm functions properly and accurately
Proof Testing - A type of stress test that uses much larger ammunition called special proof ammunition. The SAAMI are the ones performing proof tests
Jones, J. Allan. “Module 04 :: Modern Firearms Manufacture” Firearm Examiner Training, projects.nfstc.org/firearms/.