A firearm is a tube-shaped weapon designed to launch projectiles at high speed through the ignition of an explosive powder. They are renowned not only for their destructive power, but for being markedly easier to use, carry, and conceal than most melee weapons.
In the world of One Piece, firearms are extremely popular weapons, second only to swords. Fighters who specialize in the use of firearms in combat are generally known as Gunmen. Particularly skilled gunmen tend to be Snipers as well.
At the world's current technological level, the typical firearm is a flintlock (フリントロック Furintorokku?), consisting of a single tube—commonly called the "barrel"—tapering into a wooden handle at one end. This tube is rigged with four external mechanisms:
- A flashpan (or firegrate), which holds the powder that launches the projectile
- A serpent, which holds a shard of flint that ignites the powder
- A frizzen, which keeps the powder in the flashpan from spilling out and provides a steel surface for the flint to spark against
- A trigger, which allows a single pull of the finger to move the serpent into igniting position
Most often, flintlocks are loaded with round shot—solid spherical projectiles made of metals such as iron or lead. In normal circumstances, these can easily break flesh and bone, and cause immediate death if launched against a vital organ. Additionally, more advanced models may utilize pointed (also known as "conical") or explosive shot for increased power. Unlike in real-life, flintlocks in One Piece world are much more advanced as they can be shot semi-automatically like modern pistols.
However, these advantages are not absolute, and may be counteracted by any number of defenses, from armor to Devil Fruit abilities to simply well-honed reflexes. In addition, particularly durable, determined, and/or lucky individuals have been known to survive even multiple shots at point-blank range without any of these measures. Finally, like all projectile weapons, flintlocks can only hold a limited number of shots at any given time, and are not easily reloaded.
(It remains unknown whether flintlocks also become ineffective in the rain or otherwise damp conditions, as their real-life counterparts—even when users took measures to keep the flashpan dry—frequently did.)
Despite these drawbacks, flintlocks and firearms in general continue to be widely used by civilians, outlaws, and professional soldiers of every standing, and are heavily associated with power even by combatants who favor other (or no) weapons. Some—particularly Monkey D. Luffy—have been known to name their attacks after various makes and models.
The basic technology behind firearms has been used to craft many distinct weapons, of widely varying size, power, and capabilities.
A pistol (ピストル Pisutoru?), in the broadest sense, is any firearm designed to be held and operated in one hand. More technical definitions tend to identify them (in contrast to revolvers) with internal ammunition chambers, fully integrated with the firing barrel.
Pistols are the smallest, lightest, and simplest type of firearm, and correspondingly the type most often seen in civilian hands. However, they are far from unknown to seasoned combatants (who often wield specialized models, such as dual-barrels that fire two shots at once).
- Yellow Gun (黄色い銃 Kīroi Jū?): A pistol shaped like the number "7", and is designed to fire dice-shaped bullets that explode on impact. Used by Mr. 7.
- Gero Gero Gun (ゲロゲロ銃 Gerogero Gan?): A pistol with a muzzle shaped like a frog's head, and fires frog-shaped bullets that explode on impact. Used by Miss Father's Day.
- Flash Guns (
閃光銃Furasshu Gan?): Dual-barreled flintlocks with ornate design, and Flash Dials installed within to hide the shots with a flash. Braham uses two of them.
Other Notable Pistols
- Helmeppo threatened to shoot Koby with a pistol during the Romance Dawn Arc.
- Yasopp wielded a pistol during Luffy's childhood, and often demonstrated his sharpshooting to the young would-be pirate.
- Kaya's mansion staff—particularly Merry—carried pistols to ward off intruders.
- Kaya herself took one to confront Kuro with, after learning of his true intentions, but was easily disarmed.
- Don Krieg wields two dual-barreled pistols to supplement the ten gun barrels installed directly in his armor.
- Gin used a dual-barreled, shotgun-like pistol to take Zeff hostage.
- Arlong used a pistol to execute Bell-mère.
- Dr. Hiriluk regularly carried a pistol in his "medical" bag. While he identified it as a tranquilizer gun, this may have been a lie, as he drew blood when firing it at Tony Tony Chopper.
- Nero wielded a pair of Derringer-esque pistols to compensate his lack of Shigan.
- World Nobles wield gold-plated single-barreled pistols. Aside from its more grandiose-color, it functions no different than the standard flintlock gun. Saint Charlos wielded such firearm, and (in the anime) so did Saint Mjosgard.
- Caesar Clown wielded a double-barreled pistol on Punk Hazard.
- Donquixote Doflamingo wields a single-barreled, obsidian black pistol with luxurious gold plating. He loaded it with lead bullets to inflict lead poisoning.
- Capone Bege used a flintlock pistol to execute Pekoms at Whole Cake Island.
A revolver (リボルバー Riborubā?) closely resembles a pistol in size and shape, but carries its ammunition in an external cylinder with multiple chambers. To fire, a loaded chamber must individually align with the barrel; after a chamber has expended its shot, the cylinder is rotated (either manually or by trigger pull, depending on the specific design) until the next chamber aligns.
Though more internally complex—and thus, more difficult to maintain and repair—than most pistols, revolvers are also sturdier, and able to carry more powerful shots.
- Flintlock .44 Caliber 6 Shot Revolver (フリントロック式44口径6連発リボルバー Furintorokku Shiki Yonjūyon Kōkei Rokurenpatsu Riborubā?): A new model from the South Blue, capable of rapid-fire with six chambers. Used by Mr. 5, who provides ammunition via his Devil Fruit powers.
- Walker .36 Caliber Percussion Revolver (?): A powerful handgun. One is owned by Charlotte Pudding, who loaded hers with "candy-jacketed bullets"
Other Notable Revolvers
A rifle (ライフル Raifuru?) is a long-barreled firearm designed for more accurate long-distance shooting. Due to their size, rifles are typically operated with two hands, and mounted on the shoulder (or some other stable surface) when in use.
(It should be noted that "rifle" technically refers to a specific type of barrel design that fits the barrel's interior with spiral grooves, producing a spinning and stronger shot. However, common parlance has accepted it as a generic term for almost any long-barreled firearm, including "smoothbore" designs.)
Other Notable Rifles
- Benn Beckman carries a rifle as his primary weapon; though he has only been seen using it as a makeshift club in battle, he has implied at least twice that it is still in firing condition.
- Raki wielded a rifle throughout the Shandia raids on Upper Yard.
- Foxy used a rifle to non-fatally wound Shelly.
- Hammond wields a rifle modified to fire trawl nets.
- Hody Jones killed Otohime with a rifle.
- The Yeti Cool Brothers' rifles, which can fire specialized rounds.
- Kurozumi Orochi used a rifle to execute Shimotsuki Yasuie.
A bazooka (バズーカ Bazūka?) is a large, shoulder-mounted weapon designed to launch explosive or other specialized missiles. They are typically used against enemies or vehicles too large or well-armored for other firearms to penetrate.
(The term "bazooka", much like "rifle", once referred to a specific make of weapon, but has long since become a generic term for many different weapons sharing only a few common traits. Those of One Piece, in particular, often bear a closer resemblance to the hand-mortars of the 17th and 18th centuries.)
- Shokuatari Meatball (食あたり
砲弾Shokuatari Mītobōru?): Patty's lobster-shaped bazooka, wielded against especially dangerous visitors to the Baratie.
- Lassoo (ラッス Rassū?): Mr. 4's main firearm, designed to shoot baseball-themed time bombs. At some point it was "fed" a Zoan-class Devil Fruit.
- Burn Bazooka (
燃焼砲Bān Bazūka?): A Skypiean weapon that can launch both conventional shells and (if equipped with a properly-charged Breath Dial) huge columns of flame. Wyper is the best-known user of this weapon, though Conis also managed to acquire one by unknown means.
- KX Launcher (KXランチャー Kē-Ekkusu Ranchā?): A weapon designed to launch needle-tipped missiles carrying ultra-lethal poison, developed by Caesar Clown.
Other Notable Bazookas
- Mr. 9 and Miss Wednesday (better known as Nefertari Vivi) each wielded a bazooka while attempting to hunt Laboon.
- Genbo wielded a bazooka throughout the Shandia raids on Upper Yard. Unlike Wyper's, his appeared to have no special capabilities.
- Absalom's arm-mounted bazookas, which seems to fire based on his hand movements.
- Rindo's bazooka, which is equipped with giant harpoons in lieu of actual explosive rounds.
- Curiel's bazooka.
- Jalmack's bazooka, which takes the form of a gigantic rifle and equipped with a cross-hair.
- Mounblutain's bazooka.
A Gatling gun (ガトリング銃 Gatoringu-jū?) is a multi-barreled firearm that can, through a combination of internal rotating mechanisms and gravity-fed ammunition, fire (and reload) hundreds of shots within a minute.
Due to its complex design and high capacities, the typical Gatling gun is usually even larger and bulkier than a bazooka. As a result, many of their wielders possess either Devil Fruit abilities (e.g. Caribou's Numa Numa no Mi) or prosthetics that can physically integrate them.
- Pell, Caribou, Coribou, Miss Friday,  Baby 5 and Queen  all wield Gatling guns, Caribou's uses a crank mechanism.
- Scotch's right arm.
- Gotti's right arm.
- Both Capone Bege and Kelly Funk have access to Tommy guns.
Certain firearms are thus far too unique or unorthodox to be classified with the above.
- Don Krieg's Wootz steel armor boasts two gun barrels under each shoulder shield, and six lining the main carapace. Through unknown means, he can fire all of these at once while wielding his dual-pistols.
- His left shoulder shield also contains many built-in projectile launchers: a large one in the center for his infamous MH-5 shell, and a dozen smaller ones along the rim for shooting spears.
- As "Mr. 8", Igaram wielded a saxophone with a built-in shotgun. He also installed multiple gun-barrels into his hair curls, loaded with explosive shot and activated by his necktie.
- Franky's cyborg body incorporates several built-in firearms, presumably fueled by Cola:
- His "BF-36" model incorporated a bazooka in his left arm ("Weapons Left"), an explosive pellet-launcher in his left wrist ("Beans Left"), a pistol in his left index finger ("Ouch Finger"), and mini-cannons in his shoulders ("Franky Destroyer Cannon").
- His current "BF-37" model incorporates multiple gun barrels in his left knuckles ("Weapons Left"), as well as cannons and rocket launchers in his shoulders ("Franky Rocket Launcher/Cannon").
- Duval's harpoon gun, which shoots harpoons laced with scorpion venom.
- Saint Rosward possesses a cane gun, presumably for self-defense.
- Jigoku Benten of the Orochi Oniwabanshu fights with a concealed gun that is hidden inside a biwa instrument.
Notable firearms wielded by non-canon characters or characters that are not shown wielding them in the manga.
Artillery refers to heavy military ranged weapons. They're not usually meant for handheld purposes, unlike firearms.
A cannon (砲 Hō?) is an often large, heavy piece of artillery that uses explosive material, such as gunpowder, to launch projectiles of considerable size compared to bullets, such as cannonballs or bombshells. Cannons can be mobile or stationary, and may vary in size, sometimes requiring the operation of more than one individual to work properly. Cannons predated portable firearms for several years, having been an indispensable weapon in military and naval warfare through centuries due to their power and range.
Cannons also see widespread use throughout the series, as practically every ship is equipped with at least one cannon as a defensive measure, be they Pirate or Marine ships. Most crews have one or many people whose jobs are to maintain and operate the cannons. These people have been referred to as Cannoneers. Crews may have at least one or multiple cannoneers, depending on the the size of the crew and the numbers of cannons available on a ship. The number of ships under a crew's control plays a factor too, with examples including Marine Fleets and pirate fleets who have several members operating the cannons. Marine cannons appear to be more technologically advanced as they can function like gun turrets, allowing for better aiming. The Beasts Pirates, meanwhile, have special long-ranged cannons that can fire precise shots from afar. Cannons are also commonly found in other military structures such as Marineford.
- Royal Drum Crown 7-Shot Bliking Cannon (ロイヤルドラムクラウン７連
散弾ブリキング 大砲Roiyaru Doramu Kuraun Nana-ren Shotto Burikingu Kyanon?): A multi-barreled cannon owned by Wapol, having been stored somewhere in his former castle.
- Demi Cannon (デミ・キャノン Demi Kyanon?): A cannon meant to be installed onto ships, used as a handheld cannon by Tilestone.
- Gaon Cannon (ガオン砲 Gaon Hō?): A cannon that fires a powerful air blast.
- King Cannon (キング砲 Kingu Hō?): A non-canon cannon mounted on a four-wheeled tank, capable of firing devastating shells.
Mortars are weapons that function very similarly to cannons, the major difference being that mortars require a supporting bipod and an aiming device to properly work.
The Marines stationed in the Sabaody Archipelago have access to mortars, which they attempted to use on the three pirate captains identified as the perpetrators of the incident involving the World Nobles in the Human Auctioning House. The mortars ended up ineffective, however, as the captains were able to counter the explosives fired at them with their own Devil Fruits.
A tank is an armoured vehicle usually equipped with a mounted cannon and treads that allow it to traverse rough terrain.
A railgun is a weapon that utilizes electromagnetic forces instead of gunpowder to fire a high velocity projectile.
Eustass Kid, thanks to his devil fruit abilities, is capable of forming fully functional railguns through his Damned Punk technique, using scrap metal to build the actual device and charging it with the electromagnetic energy of his fruit to launch forward a devastating shot..
Translation and Dub Issues
Due to the heavy controversy surrounding gun ownership—and media depiction—in the United States, 4Kids Entertainment has used a number of different censorship methods on the many firearms featured in the anime:
- Those that inflicted no story-significant violence (e.g. Don Krieg's pistols and most Marine rifles) were usually recolored and/or modified to seem more toy-like, but allowed to fire uncensored.
- Those used in story-significant threats but not fired (e.g. Kaya's pistol) were usually replaced with "lesser" weapons such as slingshots.
- Those that inflicted story-significant violence (e.g. Arlong's pistol) were usually removed entirely, and the corresponding scenes rewritten to reduce or avert the violence.
Dialogue was also thoroughly censored to remove most explicit mentions, and firearms-themed attacks often renamed. Luffy's Gomu Gomu no Pistol, for instance, was changed to Gum Gum Blast.
- Guns and gunplay have fascinated Eiichiro Oda from a young age, tying into his love of Westerns. Indeed, his debut work Wanted! (predating One Piece by nearly five years) starred an outlaw gunslinger as the protagonist.
- Several attacks, such as Luffy's Gomu Gomu no Grizzly Magnum, are named after models and concepts introduced long after flintlocks became obsolete in real life. Whether this means models like the LAR Grizzly Mag pistol (or some in-story equivalent) exist in the world of One Piece remains to be seen.