The Hellsing ARMS 13 mm Auto Anti-Freak Combat Pistol, Jackal (usually referred to as simply "The Jackal") is a specialized firearm and one of Alucard's personal weapons.
The Jackal is a massive pistol made especially for Alucard. With a length of 39cm (16 in), a weight of 16kg (35lbs), and a black gunmetal construction, it is one of the most powerful hand weapons featured in the series. The words Jesus Christ is in Heaven Now are engraved upon it, in mockery of a similar statement on Alexander Anderson's gloves.
Its unique design makes it seem as if it doesn't have a pistol slide; however, the entire upper assembly is the slide, and moves only a minimal distance compared to other guns', making it appear as if there is no pistol slide. The Jackal has its silver ejector port on the left side, implying that it is meant to be used in conjunction with the Casull (sending the shells to the left prevents them from obscuring the wielder's view), and in the manga and anime, Alucard is usually shown wielding both guns at once.
In Hellsing: Volume 9, it was revealed that the Jackal had a explosive device hidden inside of it by the Doctor, who could detonate it with his remote if Alucard was to gain a significant edge against Millennium with it. Because of this reveal, it is possible that Walter was in ranks of Millennium when Alucard left for Rio de Grande.
The Jackal was the result of Alucard's request to Walter for "something bigger" after his Casull proved largely useless against Alexander Anderson. The butler delivered in full with the creation of the Jackal; in fact, the inscription on its side implies that it was meant especially to end Anderson's life. Alucard would repeatedly express his satisfaction with the new firearm, declaring that it was "perfect".
At the time the Jackal was ordered, Walter was a secret agent for Millennium and had constructed the gun for Alucard. Alucard used it in every fight after his first encounter with Anderson, except with Rip van Winkle, whom he bested with bare hands. The end of the Jackal's formidable battle power came when Alucard returned to England. In the London battle, the Doctor activated the explosive failsafe, permanently destroying it. It is not known whether its reconstruction was attempted after the siege of London.
The Jackal fires a huge, armour-piercing, thirteen-millimeter bullet. The rounds are jacketed with a "casing" of blessed Macedonian silver and tipped with a hollow point, which contains an explosive charge of pre-blessed mercury.
The rounds use "Marvell's Chemical Cartridge N.N.A.9", and are suggested to be very short by the minimal movement of the Jackal's slide. This could be due to the cartridge being powerful enough to require only minimal propellant. However, the high calibre-bullets also have a downside; their great size limits the Jackal's magazine capacity to six rounds.
The bullets were designed primarily to be used against Iscariot's top agent, Alexander Anderson, who shrugged off the Casull's rounds with ease. They proved powerful enough to negate Anderson's great regenerative abilities for at least a significant amount of time - notably, a Jackal bullet inflicted severe damage to Anderson's left arm that did not recover until the paladin used Helena's Nail to enhance his regeneration.
However, the Jackal's ammunition also makes for an extremely effective anti-vampire combat weapon in general. Like the Casull, Alucard has reloaded the Jackal various times, but has also greatly exceeded the number of rounds per magazine. The reason he is able to do this is never explained but in the back of volume 1, Kouta Hirano has jokingly stated that "They're all cosmoguns that can hold a million rounds".
The power of Jackal is much greater than Casull's. It was made specially for fighting Anderson who was stubborn enough to survive bullets from Casull. During Alucard and Anderson's duel in London, the Jackal was able to nearly sever his arm. Later on, a single shot was able to blow Anderson's head completely off from the lower jaw up, despite the bullet striking him on only the left side of the face. However, the Paladin's head regenerated due to the Nail of Helena.
When Alucard fought with Luke Valentine, he easily dodged all of Alucard's shots, but when Alucard used the Jackal he barely dodged its bullet. The wall that the bullet hit was totally destroyed.
The Jackal is named after the eponymous antagonist of The Day of the Jackal, a famous English-French movie released in 1973. In the movie, Jackal was a fictional assassin hired to kill Charles de Gaulle, France's President between 1959-1969. As it's revealed in one of Alucard's dreams in Volume 5, the Jackal is the spirit of the pistol named after him (like the Dune-character Baron Vladimir Harkonnen is the spirit of Seras Victoria's cannon). In this dream, Jackal can even successfully kill the criticized remake's leading actor, Bruce Willis (ironically, he misses De Gaulle).
In the Anime TV series, The Jackal was intended "to kill" Anderson, which didn't happen in the series, as he only injured Anderson's both arms severely, instead it outlived its purpose in killing Incognito.