steel frame. These weapons may fire factory-made or improvised rounds, and can contain many different explosive fillers and firing mechanisms. “Barrack buster” is the colloquial name given to several improvised mortars developed in the 1990s by the Provisional Irish Republican Army (PIRA) during The Troubles. There was several different versions of these mortars constructed by the PIRA, with the most commonly used being the Mark 15 320mm mortar, which fired a projectile constructed of a gas cylinder filled with 196-220 pounds (89-100 kg) of homemade explosives which was remarked as having the effect of a “flying car bomb”, and was used in several different attacks on British Army and RUC bases. It was also used in attacks on a number of British helicopters, two of which were successfully shot down in 1994; a British Army Westland Lynx multipurpose helicopter, and an RAF Aérospatiale SA 330 Puma transport helicopter. Several other types of improvised mortars were created by the PIRA during the Troubles, including the “Mark 16” or “Projected Recoilless Improvised Grenade”, which was used more like a rocket launcher and fired a projectile made of a tin can filled with 600g of Semtex, the “Mark 12” or “Improvised Propelled Grenade” which fired a 40 ounce (1.1 kg) warhead horizontally at security forces bases and vehicles, and the “Mark 10”, which fired a 44–220 pound (20–100 kg) warhead, one of which was responsible for the first intentional killing of a British soldier in a mortar attack. Because of the weight of these mortars, they often had to be transported on vehicles such as tractors and vans. Improvised artillery has been used extensively by various factions of the Syrian opposition during the Syrian civil war as a way of making up for deficits in the quantity of military-grade artillery. These “Hell Cannons”, as they are known, have been used by various anti-government and Jihadist groups and can fire both improvised and factory-made rounds. The first of these weapons were made in 2012 by the Islamist Ahrar al-Shamal Brigade in the Idlib Governorate around the city of Binnish before the manufacturing was moved to Aleppo by the Free Syrian Army’s 16th Division which also appropriated the design. The knowledge spread to other groups in Syria, including the Islamic State of Iraq and the Levant. Variants of these cannons have also been developed by rebel forces, including the “Thunder Cannon” made from the body