missions as it is possible for the ammunition to keep up with the guns. A modern battery of six guns, each firing 43 kg projectiles with a burst firing speed of four rounds per minute, can deliver over a tonne of ordnance per minute for up to four minutes. This is an immense weight of fire, which can be delivered with very high accuracy. One example of the increased firepower provided by modern mobile howitzers is the latest version, the G6-52, of the 155 mm G6 howitzer. It can fire up to six rounds in quick succession that will land nearly simultaneously. This is achieved by firing the shells at different trajectories so that the first round has the longest flight time and the last round the shortest. This is an improvement of the concept of MRSI (Multiple Rounds Simultaneous Impact), itself an enhancement of the earlier TOT (Time On Target) concept. The necessary rapid reloading is made possible by an automated ammunition feed system. Rockets and missiles Rockets have greater ranges and carry much more complex "shells" than guns since there is less of a restriction on size (calibre). The MLRS can be used to saturate a large area with sub-munitions. See also List of artillery List of self-propelled howitzers Howitzer Self-propelled anti-aircraft weapon Tank destroyer Assault gun G-numbers – US military vehicle and related supply designations Notes Sources External links Overview Self-propelled artillery Systems at www.dtig.org Combat vehicles by type Weapon fixtures English inventions