Unidentified master gunnery sergeant
From Halopedia, the Halo wiki
This unidentified master gunnery sergeant was a non-commissioned officer in charge of Cairo Station's armory. On October 20, 2552, he helped Spartan-II John-117 get used to his new Mark VI MJOLNIR armor.
Some time after John-117 arrived at Cairo Station, the NCO fitted the Spartan with the Mark VI armor that Maria-062 had tested earlier in the day at SWC Songnam. The MGySgt was initially annoyed with how much damage the Master Chief's old Mark V armor had taken, but then admitted that the Mark V technology was obsolete. He then tested the new armor's optics and energy shielding. Sergeant Major Avery Johnson soon arrived at the armory to lead John-117 to the ceremony held in the orbital platform's bridge. When the MGySgt asked how Johnson had survived the Battle of Installation 04, the sergeant major replied that such information was classified. Angered, "Master Guns" replied that he would not make the adjustments to Johnson's A2 scope that he was apparently set to perform.
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