The double-action revolver is a design almost as old as the single action. revolvers can only be fired using the trigger (e.g., revolvers with bobbed or hidden hammers).
With this, the three basic features of the gun emerged: a barrel made of metal, high-nitrate gunpowder, and a projectile which totally occludes the muzzle so that the powder charge exerts its full potential in propellant effect.
The oldest surviving firearm is the Heilongjiang hand cannon dated to 1288, which was discovered at a site in modern-day Acheng District where the History of Yuan records that battles were fought at that time; Li Ting, a military commander of Jurchen descent, led footsoldiers armed with guns in battle to suppress the rebellion of the Christian Mongol Prince Nayan. al-Hassan claims that the Battle of Ain Jalut in 1260 saw the Mamluks use against the Mongols "the first cannon in history" with gunpowder formula which are almost identical with the ideal composition for explosive gunpowder.
these inventions were later transmitted to the Middle East, Africa, and Europe.
The direct ancestor of the firearm is the fire lance.
There are also "single- shot" and multiple barrel firearms, which hold only one cartridge per barrel and must be reloaded manually between shots.
The earliest repeating firearms were revolvers (revolving rifles were sometimes called "turret guns") and were "single action" in that they could only be fired one way: by manually cocking the mechanism (drawing the hammer to the rear with the thumb) before each shot.A revolver is a unique type of firearm in which a rotating cylinder holds a number of cartridges; the cylinder "revolves" to align each "chamber" or "charge hole" with the rear of the barrel, hold the cartridge and contain the pressure (up to 65,000 pounds per square inch or 450 MPa) produced when the cartridge is fired.Thus the cylinder serves as both magazine and firing chambers.During the early modern age, these hand-held cannons evolved into the match lock, wheel lock,dog lock, and flintlock rifle, respectively, then the breech loader and finally the automatic weapon.As ignition devices, matchlocks, wheellocks, snaplock, flintlocks and percussion caps were used in turn.It is operated by a hand crank and rotates multiple barrels.