"Home-made" mortars have been used by insurgent groups. They are usually used to attack well defended military bases or to scare civilians. An early example was the Davidka. This was used during the Israeli War of Independence in 1948. The Provisional Irish Republican Army used some of the best-known examples during the 1970s, 1980s and 1990s. The biggest types came to be known as "barracks busters". They were usually made of heavy steel piping put onto a steel frame.