Decoppering

{{Unreferenced, date=December 2009 Decoppering is the act of removing

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

and it is most commonly used in the context of the removal of copper residues from the

rifling In firearms, rifling is machining helical grooves into the internal (bore) surface of a gun's barrel for the purpose of exerting torque and thus imparting a spin to a projectile around its longitudinal axis during shooting to stabilize the pro ...

gun barrel A gun barrel is a crucial part of gun-type weapons such as small firearms, artillery pieces, and air guns. It is the straight shooting tube, usually made of rigid high-strength metal, through which a contained rapid expansion of high-pressure ...

s. Decoppering agents are frequently added to

smokeless powder Finnish smokeless powderSmokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to gunpowder ("black powder"). The combustion products are mainly gaseous, compared to a ...

propellant A propellant (or propellent) is a mass that is expelled or expanded in such a way as to create a thrust or other motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the e ...

s. Decoppering is most important for large guns (especially

naval gun Naval artillery is artillery mounted on a warship, originally used only for naval warfare and then subsequently used for naval gunfire support, shore bombardment and anti-aircraft roles. The term generally refers to tube-launched projectile-firi ...

s), but the additives are used even in medium and small caliber guns. The most common decoppering additives are: *

Tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

metal and compounds, e.g.

tin dioxide Tin(IV) oxide, also known as stannic oxide, is the inorganic compound with the formula SnO2. The mineral form of SnO2 is called cassiterite, and this is the main ore of tin. With many other names, this oxide of tin is an important material in tin ...

Bismuth Bismuth is a chemical element with the Symbol (chemistry), symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental ...

metal and compounds, e.g.

bismuth trioxide Bismuth(III) oxide is perhaps the most industrially important compound of bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resem ...

bismuth subcarbonate Bismuth subcarbonate (BiO)2CO3, sometimes written Bi2O2(CO3) is a chemical compound of bismuth containing both oxide and carbonate anions. Bismuth is in the +3 oxidation state. Bismuth subcarbonate occurs naturally as the mineral bismutite. Its ...

bismuth nitrate Bismuth(III) nitrate is a salt composed of bismuth in its cationic +3 oxidation state and nitrate anions. The most common solid form is the pentahydrate. It is used in the synthesis of other bismuth compounds. It is available commercially. It is th ...

bismuth antimonide Bismuth antimonides, Bismuth-antimonys, or Bismuth-antimony alloys, (Bi1−''x''Sb''x'') are binary alloys of bismuth and antimony in various ratios. Some, in particular Bi0.9Sb0.1, were the first experimentally-observed three-dimensional topologi ...

; the bismuth compounds are favored as copper dissolves in molten bismuth, forming

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Bre ...

and easily removable

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

Lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

foil and lead compounds, now phased out due to lead toxicity Ammunition