The Projected Recoilless Improvised Grenade (PRIG) was a shoulder fired weapon developed by the Provisional Irish Republican Army (PIRA) for use against lightly armored vehicles. It is perhaps the most ingenious example of kitchen cupboard improvisation to date.

The launcher consisted of a length of steel tube adapted to accept a charge of black powder in the middle by way of a capped off perforated pipe welded in place. The charge is wired to a simple circuit, often utilizing a light bulb holder as an arming switch and fired by a long arm micro-switch which serves as a trigger.

The warhead itself consists of a standard food tin filled with 600g of Semtex, complete with an internal frontal metal cone creating an armor piercing shaped charge. This round was designed to explode on impact, being an adaption of an earlier used improvised anti-armour stick-grenade known as a ‘drogue bomb’ which after releasing the fly off lever ejected a stabilizing drogue made from a trash bag.

To the rear of the launcher was placed the ‘counter-shot’, incorporated to utilize the recoilless principle (Reduced to as little as a .22lr rifle’s, according to some!). This consisted of two packets of digestive tea biscuits, wrapped in j-cloth…. an interesting forensic aftermath of course ensues!

This weapon was used in at least eleven attacks during the early 1990s, and can often be seen touted out in IRA training footage.

A more compact variation:

A further simplified version trialled in the book ‘Improvised Home-built Recoilless Launchers’:

An earlier attempt at a clandestinely produced launcher was the IPG (Improvised Projected Grenade). A downside to this design was that the shoulder bruises incurred after firing apparently had the side effect of aiding the authorities in identifying the shooter if he were searched.

The pinnacle mortar development in the IRA’s arsenal was the Mark-15 ‘Barrack Buster’ – a large Calor propane gas cylinder adapted to fire a smaller cylinder filled with up to 100kg of explosive material. This model was used to bring down two British army helicopters and similar variations were occasionally fired in batteries of up to 12 units.

An IRA video showing a successful firing of the Mark-15:

The aftermath of a ‘truck donor’ having experienced one firing: