THE Model 82 Barrett, known as the "light 50", is, in terms of its range and impact, placed somewhere between a high velocity rifle and a shoulder launched missile.
Sales literature on the Barrett suggests it is an ideal weapon for use against armoured personnel carriers, radar dishes, communications vehicles, even aircraft, as well as human targets.
It has achieved "confirmed" hits at 1,800 metres, well over a mile, with a maximum range of 6.800 metres.
It is capable of piercing all body armour and, with special armourpiercing munitions, most vehicle armour.
It is five feet long but can be "field stripped" for easy transportation in 15 seconds. It sells for $6,750.
It is believed one of these weapons was used by an Israeli Defence Forces (IDF) sniper to shoot dead a leading Hizbolluh official in south Lebanon, while the man was driving his car, from a distance of more than 1,000 metres.
The IRA team which has been using the weapon in south Armagh has operated from much closer ranges.
The IRA tactic has been to place the gun in the rear of a car, drive to within easy range of the target, fire and drive off. The rear of the car is arrnoured with steel plate to protect it from gunfire from the rear.
By 1993, the Barrett had become the most deadly weapon used by the IRA against the security forces in Northern Ireland.
Nine of the 14 security force members killed in 1993 were shot by the south Armagh sniper using the Barrett light 50 or some other sniping rifle.
There is almost no means of protecting security force members operating in the open from a weapon like the Barrett.
Its massive power and accuracy ensure, as one American weapons commentator puts it, that a hit "will end all voluntary muscular activity". In other words, a single shot kills regardless of whether the victim is wearing "bullet proof" jackets or helmets.
Any security force member operating in the south Armagh south Down area knew he or she was vulnerable, no matter what the circumstances.
RUC Constable Brian Woods was shot dead while he was on point duty at an interdenominational peace service in Newry on November 30th, 1993.
The IRA acquired the Barrett in response to developments in bullet proof clothing, which affords protection to security force members in Northern Ireland from the normal 7.62mm fired from weapons like the AK47 or Armalite rifles.
In the mid 1980s the IRA realised these weapons were no longer effective against the new body armour and directed its arms procuring teams in the United States to acquire the Barrett.
One Barrett was bought in 1986 but was seized by gardai when an attempt was made to post it to Dublin. It was intercepted at the Central Sorting Office.
Further attempts were made by a six member IRA arms buying team which was captured by the FBI in 1989.
Part of the indictment in the case accused a Belfast man and a south Armagh man of saying to an FBI undercover agent that "there was a lot of money... if he could acquire a .50 calibre rifle ... for use against British soldiers stationed on the Border between the Republic of Ireland and Northern Ireland
The IRA men indicated they wanted three or four of the weapons, as well as a Stinger ground to air missile, according to the FBI.
It is not clear if the IRA eventually managed to acquire more than one weapon, however.