The Gunners. Basically people with training equivalent to the Brotherhood and the attitude of the common neighborhood bully. All the more reason to wage war against these savages. - General John "Putnam"
The Gunners are a mercenary organization mostly known to be based in the Commonwealth. Most known for their no prisoners mindset, their ability to wipe out entire settlements, and structured organization and advanced equipment and training, they are regarded no better than Raiders by those that oppose them.
The Gunners are a violent mercenary outfit, known to take any job so long as the price is right. They are regarded as no better than common raiders, as they attack anyone who they believe is too weak to defend themselves. So long as it benefits their agenda, the Gunners are known to target anyone.
War of the Commonwealth
The Gunners, for a part, avoided involvement in the three-way war between the Brotherhood of Steel, the Railroad, and the Institute, save for several defensive skirmishes against one or more of the three factions.
When the Minutemen launched an offensive against their primary stronghold at Gunners' Plaza, the mercenaries were able to push back the offensive and launch their own against the attacks until the pursuing forces were eliminated in the central part of the former city of Boston.
Over the last several years, while the Minutemen slowly grew in power under the direction of their new General, the Gunners also acquired new hardware for themselves. One example was their expanded Robotics after the capturing of the RobCo building (which was later known to possess a large factory underneath) and enslavement of Isabel Cruz to further their project. The Gunners also obtained copies of schematics for West-Tek optics after a skirmish against the Minutemen who were after the same technology in the northern part of the Commonwealth.
The Gunners follow a hierarchy similar to the pre-War United States Army. It is unknown which rank represents the faction's chief-of-staff, as the Gunners never reached the need for their supreme leader to appear personally. Their de facto leaders are their high-ranking Commanders, Brigadiers, and other assigned officers from their mysterious leadership.
The Gunners are known to be one of the most advanced in equipment and weapons. Conscripts and recruits will generally sport a 10mm pistol or submachinegun and a backup weapon, usually a melee weapon such as a baton. Better members (from Corporals to Commanders) carry better weapons, generally modified Assault Rifles or laser rifles. Their best field operatives (Lieutenants to Brigadiers) more or less use customized weapons of their choosing and availability. In response to the Brotherhood of Steel's power-armored soldiers and later the resurgent Minutemen, many specialized Gunners sport Anti-Materiel rifles to counter them.
Other than their equipment and training rivaling the Brotherhood, the Gunners use their newly-earned Robotics from the former Mechanist's Lair as front-line combatants.