This is not a screen used piece, but it is the exact same vest worn by Weir in Episode "Submerged" as well as this model of Blackhawk Tactical Vest has been used by a lot of others in the background. I have also confirmed with Blackhawk Tactical that they did sell over 50 vest and Tactical Holsters to the Stargate Production group (NOTE: Both the vest and and holster have been discontinued by BlackHawk Tactical.A second reference image.
