The ARWEN 37 anti-riot weapon was designed in the late 1970s, ultimately reaching adoption and production in the early 1980s. The system came about through a specialized need by British law enforcement to replace generally ineffective anti-riot weapons then in use. As tensions in Northern Ireland mounted, the need was evermore apparent in developing a new, multi-shot weapon with adequate engagement ranges and the capability to fire various types of crowd control (non-lethal) munitions. The result of this initiative was the "ARWEN 37", its design attributed to the engineers of the British Royal Small Arms Factory (Enfield) with manufacture handled by Royals Small Arms Factory. The "ARWEN" name stemmed from the acronym for "Anti-Riot Weapon, ENfield".
The finalized ARWEN 37 eventually appeared in several specialized forms to include a base/standard production model, the short-ranged ARWEN Multi-S, the ARWEN 37 Multi-V and the ARWEN ACE. The standard model was a 4.5kg offering with an overall length of 30 inches (with 11.2 inch barrel). This featured the 5-round rotating cylinder chambered for 37mm ammunition. The ARWEN Multi-S short-ranged version fielded no stock and a shorter barrel assembly for a more compact profile. The ARWEN Multi-V allowed for vehicle mounting through a ball arrangement. The ARWEN ACE became a handier single-shot alternative to the standard ARWEN 37 and also of lighter weight (2kg). However, this version is a breech-loaded weapon which requires reloading after each single shot.
The ARWEN 37 has since given a good account of itself and has expanded use beyond police services to include military-level service including that of British SAS (Special Air Service). It is regarded as a reliable and effective weapon, utilizing a repeat-fire nature which benefits the operator over the older single-shot variety weapons of similar function. Additionally, the cylinder is easily accessible for reloading as opposed to the "break action" types seen in single-shot offerings. Rate-of-fire is further improved thanks to the rotary nature of the ARWEN 37, particularly when needing the operator to lay down a protective wall of anti-riot ordnance on an advancing mob.
The weapon is produced under license in Canada and has turned up in raids across Iraq. All ARWEN models are now property of Police Ordnance Company, Incorporated.