The term built-up gun describes a construction technique for artillery barrels. An inner tube of metal which stretches most within its elastic limit enlarges under the pressure of confined powder gases to transmit stress to outer cylinders under tension. Concentric metal cylinders and/or wire windings are assembled to minimize the weight required to resist the pressure of powder gases pushing a projectile out of the barrel. Built-up construction was the norm for guns mounted aboard 20th century Dreadnoughts and contemporary railway guns, coastal artillery, and siege guns through World War II.