Homicide:
http://dictionary.reference.com/search?q=homicide+&x=0&y=01. the killing of one human being by another.
2. a person who kills another; murderer.
Under the above definition, homicides have been committed with the Barrett 50 cal. rifle. The army uses them as sniper rifles. Snipers are soldiers who believe in the "one shot, one kill" philosophy.
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The M107 .50-caliber long range rifle is semi-automatic and is being fielded to infantry soldiers. It can engage targets to 2,000 meters with precision. At 29 inches long, the frame mounted, bolt-action XM107 weighs 28.5 pounds with optics. It is manufactured by Barrett Firearms Manufacturing, Inc. The XM107 is a rapid-fire; man portable, shoulder-fired, recoil operated semi-automatic system utilizing military standard .50 caliber ammunition. The primary components of the system consist of a rifle, day optical sighting system and hard carrying case(s).
Army snipers deliver precision fire against enemy targets that are outside a rifleman's limitations of range, size, location, mobility and visibility. The M107 is derived from the M82A1 commercial version of the weapon that is manufactured by Barrett Firearms Manufacturing, Inc. of Murfreesboro, TN. It can defeat materiel targets located at distances beyond the range of the standard M24 7.62mm Sniper Weapon System, Galeazzi said. In the hands of a trained sniper, the M107 can surgically take out strategic targets while minimizing collateral damage. It is capable of hitting personnel targets as far away as 1500 meters and materiel targets out to 2000 meters.
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According to Operation Iraqi Freedom PEO Soldier Lessons Learned
"The Barrett 50 cal Sniper Rifle may have been the most useful piece of equipment for the urban fight – especially for our light fighters. The XM107 was used to engage both vehicular and personnel targets out to 1400 meters. Soldiers not only appreciated the range and accuracy but also the target effect. Leaders and scouts viewed the effect of the 50 cal round as a combat multiplier due to the psychological impact on other combatants that viewed the destruction of the target.
“My spotter positively identified a target at 1400 meters carrying an RPG on a water tower. I engaged the target. The top half of the torso fell forward out of the tower and the lower portion remained in the tower.” 325th PIR Sniper
"There were other personal anecdotes of one round destroying two targets and another of the target “disintegrating.”
http://www.globalsecurity.org/military/systems/ground/m107.htm
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In the wrong hands this could be a terrifying weapon. Imagine a freeway shooter with one.
http://www.whittierdailynews.com/crime/ci_8763987
http://www.wcsh6.com/news/article.aspx?storyid=83629
To be fair, I don't believe any have been used by common citizens to murder others in the U.S. A 50 cal. rifle would be an awkward weapon to use to hold up a convenience store and would be worth far more than any loot obtained.