I was buying things from the seller guy at Camp Mcarran (the guy waaaay in the back) and he said he will show me his special inventory if i do a mission for him, he wants me to talk to some guy in the gun runners compound about something but i cant find the guy at the gun runners, the compound is really small and only one building but no one in there has the name of the guy im looking for, any body know about this?

Gun Runner Factory or Crimson Caravan Company?
Did he say: "tell him Contreras sent you." ?
Nevermind all that

Wait a minute, that Isaac guy, right?
He's by the reloading bench by the Vendortron in the kiosk. If he's not there, then look for him in his (illegal to enter, but unlocked) house.

Yeah it was Issac ok ill check there thanks