The Mod 00 is a short-barreled, breech-loading signal pistol, which can also be used as a weapon, manufactured by SAMT-Torino since World War II. It launches its projectile in an arc, and can be used for long-range indirect fire when aimed outside of V.A.T.S. After damage caused by the initial hit, affected targets will take additional fire damage for a short time. A significant aspect of this weapon is its ammunition capacity; thought it holds ten flamer fuel, the flare gun fire all ten units at once.
The flare gun also has the ability to frighten abomination-type creatures. Whilst on fire, they will attempt to flee from the player, but will resume their normal behavior once extinguished. Note also that a fleeing creature may run right at and past the player if there is no other line of escape, but will not attack while on fire. Abominations frightened by the effects of the flare gun include deathclaws, centaurs, nightstalkers, and tunnelers.
Although classed as abominations, fire geckos are unaffected.
Behind the scenes
The object effect is named "Burninate All the Peoples", a reference to Strong Bad's Trogdor song in Homestar Runner as well as the "X ALL the Y" internet meme.
A flare gun is a real tool used in many careers, such as the police career, and in some military installations. It is used mostly as a warning sign, or a sign for help, despite its in-game use as a weapon.
↑Name printed on the side of the weapon, above the trigger