Firearm modification is commonly done in order to enhance various aspects of the performance of a firearm. Reasons for these modifications can range from cosmetic to functional, and can be simple operations that the owner can perform, or complex operations requiring the services of a

gunsmith A gunsmith is a person who repairs, modifies, designs, or builds guns. The occupation differs from an armorer, who usually replaces only worn parts in standard firearms. Gunsmiths do modifications and changes to a firearm that may require a very ...

Modifications performed

Common modifications include: * Cosmetic and ergonomic modifications ** Replacement or alteration of grips or stocks ** Changing of sights, such as the adjustable

iron sights Iron sights are a system of physical alignment markers used as a sighting device to assist the accurate aiming of ranged weapons such as firearms, airguns, crossbows, and bows, or less commonly as a primitive finder sight for optical telescop ...

or a

telescopic sight A telescopic sight, commonly called a scope informally, is an optical sighting device based on a refracting telescope. It is equipped with some form of a referencing pattern – known as a ''reticle'' – mounted in a focally appropriate p ...

** Adding or removing weight to ease carrying, alter balance, or help moderate

recoil Recoil (often called knockback, kickback or simply kick) is the rearward thrust generated when a gun is being discharged. In technical terms, the recoil is a result of conservation of momentum, for according to Newton's third law the force requ ...

** Metal engraving or custom woodwork ** Checkering or stippling wood or metal ** Altering the metal finish, using techniques such as bluing,

electroplating Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the redox, reduction of cations of that metal by means of a direct current, direct electric cur ...

, or parkerizing ** Use of a shorter barrel to reduce size and weight, or a longer barrel to increase velocity * Caliber conversions ** Rechambering or rebarreling for a new caliber, such as conversions made to chamber a

wildcat cartridge A wildcat cartridge, often shortened to wildcat, is a custom-made cartridge (weaponry), cartridge for which ammunition and/or firearms are not mass-produced. These cartridges are often created as experimental variants to optimize a certain ballis ...

** Use of a caliber conversion sleeve or other readily removable insert to fire a smaller, less expensive cartridge * Operating mechanism conversions **

Muzzleloading Muzzleloading is the shooting sport of firing muzzleloader, muzzleloading guns. Muzzleloading guns, both antique and reproduction, are used for target shooting, hunting, historical re-enactment and historical research. The sport originated in the ...

paper cartridge A paper cartridge is one of various types of small arms ammunition used before the advent of the cartridge (firearms), metallic cartridge. These cartridges consisted of a paper cylinder or cone containing the bullet, gunpowder, and in some case ...

to metallic cartridge conversions, such as the Allin conversion or Lund conversion ** Conversion from fully automatic or

select fire Select or SELECT may refer to: Arts, entertainment, and media * Select (album), ''Select'' (album), a 1982 album by Kim Wilde * Select (magazine), ''Select'' (magazine), a 1990–2001 British music magazine * ''MTV Select'', a 1996–2001 interac ...

to semiautomatic only or manual operation, or vice versa ** Short recoil to blowback conversions, used in various .22 Long Rifle conversions, such as the

Colt Ace The Colt Ace or Colt Service Model Ace is a Colt Model 1911-derived semi-automatic pistol, semi-automatic firearm chambered for the .22 Long Rifle cartridge instead of .45 ACP. It was created in 1931 and produced through 1947 to allow inexpensive ...

and J. A. Ceiner conversion kits. ** Conversion from

handgun A handgun is a firearm designed to be usable with only one hand. It is distinguished from a long gun, long barreled gun (i.e., carbine, rifle, shotgun, submachine gun, or machine gun) which typically is intended to be held by both hands and br ...

carbine A carbine ( or ) is a long gun that has a barrel shortened from its original length. Most modern carbines are rifles that are compact versions of a longer rifle or are rifles chambered for less powerful cartridges. The smaller size and ligh ...

rifle A rifle is a long gun, long-barreled firearm designed for accurate shooting and higher stopping power, with a gun barrel, barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus o ...

** Addition of a rifled barrel to a

shotgun A shotgun (also known as a scattergun, peppergun, or historically as a fowling piece) is a long gun, long-barreled firearm designed to shoot a straight-walled cartridge (firearms), cartridge known as a shotshell, which discharges numerous small ...

to allow it to better fire

shotgun slug A shotgun slug is a heavy projectile (a slug) made of lead, copper, or other material and fired from a shotgun. Slugs are designed for hunting large game, and other uses, particularly in areas near human population where their short range and slo ...

s *

Accurizing Accurizing is the process of improving the accuracy and precision of a gun (firearm or airgun). For shooting sport, accuracy is the gun's ability to hit exactly what the shooter is aiming at, and precision is the ability to hit the same place ov ...

* Sporterizing Some commonly customized firearms include the Ruger 10/22 carbine, the

M1911 pistol The Colt M1911 (also known as 1911, Colt 1911, Colt .45, or Colt Government in the case of Colt-produced models) is a single-action, recoil-operated, semi-automatic pistol chambered primarily for the .45 ACP cartridge. History Early histo ...

, and the AR-15 rifle, all of which have large numbers of aftermarket parts suppliers. Shooting disciplines such as bullseye pistol and

benchrest shooting Benchrest shooting is a shooting sport discipline in which high-precision rifles are rested on a table or benchrather than being carried in the shooter's handswhile shooting at paper or steel targets, hence the name "benchrest". Both the fo ...

also rely extensively on custom-built and modified firearms to achieve top accuracy.

Legal issues

Care must be taken when modifying firearms, as some operations may convert a legal firearm into an illegal one. An example of this is the restrictions in the US

National Firearms Act The National Firearms Act (NFA), 73rd Congress, Sess. 2, ch. 757, was enacted on June 26, 1934, and currently codified and amended as . The law is an Act of Congress in the United States that, in general, imposes an excise tax on the manufact ...

, which define restricted classes of firearms. Examples of illegal firearms under this act are: *Rifles with overall lengths under 26 inches, or barrels under 16 inches in length *Shotguns with overall lengths under 26 inches, or barrels under 18 inches in length * Machine guns *A conversion to a fixed cartridge of over .50 caliber These restrictions vary from location to location; some areas may restrict

magazine A magazine is a periodical literature, periodical publication, print or digital, produced on a regular schedule, that contains any of a variety of subject-oriented textual and visual content (media), content forms. Magazines are generally fin ...

capacity or require special safety devices such as

loaded chamber indicator Close-up shot of a safety of an M16A2 rifle In firearms, a safety or safety catch is a mechanism used to help prevent the accidental discharge of a firearm, helping to ensure safer handling. Safeties generally can be divided into subtypes su ...

s, integral locking mechanisms, magazine disconnects. Also commonly required are identifying marks such as serial numbers or firearm microstamping components, removal of which may be illegalSee

Gun Control Act of 1968 The Gun Control Act of 1968 (GCA or GCA68) is a U.S. federal law that regulates the firearms industry and firearms ownership. Due to constitutional limitations, the Act is primarily based on regulating interstate commerce in firearms by general ...

Furthermore - conversion of semi-automatic weapons into select-fire weapons has been illegal for non- SOT holding gunsmiths since the passage of the Hughes Amendment in 1986. Such weapons may be held only by law enforcement and military only except for "dealer samples" left in the hands of SOT holders. Fully automatic weapons converted to semi-automatic only operation are machine guns per the NFA. The BATFE's policy is "Once a machine gun, always a machine gun."

References

Firearm terminology

Modifications performed

Legal issues

See also

References