How gun is made?
The simplest of guns can be made with a strong tube (barrel), a
propellant and a projectile. Modern firearms have taken this basic
concept to impressive lengths. Modern firearms are created using a
variety of metals & materiel and specialized milling machines,
and modern projectiles (which contain the propellant and a
suitably-safe initiator) account for the costs of a finely-tuned
machine. Even little improvements, such as placing grooves inside
the barrel--originally to collect black powder residue, but soon an
increase in projectile accuracy was discovered (rifling). Still,
the largest naval gun or the smallest modern handgun have the same
basic features: a tube, some propellant & a projectile.