Barrack buster is the colloquial name given to several improvised mortars, developed in the 1990s by the engineering unit of the Provisional Irish Republican Army (IRA).

[1] The Mark 15 was first used in an attack on 7 December 1992 against an RUC/British Army base in Ballygawley, County Tyrone,[1][2] The projectile, fired from a tractor parked near the town's health center, was deflected by the branches of a tree besides the perimeter fence.

The first such mortar—Mark 1—was used in an attack in May 1972 and it was soon followed by the first of a series of improved or differentiated versions stretching into the 1990s: The intensification of the IRA's mortar campaign in the late 1980s led the British government to increase the number of army troops in Northern Ireland from its lowest ebb of 9,000 in 1985 to 10,500 in 1992.

[29] The IRA's use of mortars combined with heavy machine guns compelled the British Army to build their main checkpoints more than a mile away from the Irish border by 1992.

[36] The possible transfer of this mortar technology to the FARC was a central issue in the arrest in August 2001 and later trial of the so-called Colombia Three group of IRA members, who were found innocent of false claims by Colombian authorities and the United States House Committee on Foreign Affairs that they “allegedly” trained FARC in the manufacture and use of this mortar technology even though there was no evidence presented at trial to prove the claim.