[2] Firearm muzzle velocities range from approximately 120 m/s (390 ft/s) to 370 m/s (1,200 ft/s) in black powder muskets,[3] to more than 1,200 m/s (3,900 ft/s)[4] in modern rifles with high-velocity cartridges such as the .220 Swift and .204 Ruger, all the way to 1,700 m/s (5,600 ft/s)[5] for tank guns firing kinetic energy penetrator ammunition.
Several factors, including the type of firearm, the cartridge, and the barrel length, determine the bullet's muzzle velocity.
[7] For projectiles in unpowered flight, its velocity is highest at leaving the muzzle and drops off steadily because of air resistance.
Some high-velocity small arms have muzzle velocities higher than the escape speeds of some Solar System bodies such as Pluto and Ceres, meaning that a bullet fired from such a gun on the surface of the body would leave its gravitational field; however, no arms are known with muzzle velocities that can overcome Earth's gravity (and atmosphere) or those of the other planets or the Moon.
While traditional cartridges cannot generally achieve a Lunar escape speed (approximately 2,300 m/s [7,500 ft/s]) or higher due to modern limitations of action and propellant, a 1-gram (15-grain) projectile was accelerated to velocities exceeding 9,000 m/s (30,000 ft/s) at Sandia National Laboratories in 1994.
This discovery might indicate that future projectile velocities exceeding 1,500 m/s (4,900 ft/s) have to have a charging, gas-operated action that transfers the energy, rather than a system that uses primer, gunpowder, and a fraction of the released gas.
This may be another indication that future arms developments will take more interest in smaller caliber rounds, especially due to modern limitations such as metal usage, cost, and cartridge design.
[8] In conventional guns, muzzle velocity is determined by the quantity of the propellant, its quality (in terms of chemical burn speed and expansion), the mass of the projectile, and the length of the barrel.
Consequently, propellant quality and quantity, projectile mass, and barrel length must all be balanced to achieve safety and to optimize performance.
This gas was created following the trigger being pulled, causing the firing pin to strike the primer, which in turn ignited the solid propellant packed inside the bullet cartridge, making it combust while situated in the chamber.