The McCoys ship low-grade chems and occasional meds from the NCR to the suburban wasteland.
Until the Consortium opened for business, the McCoys held a virtual monopoly on the chem trade – and they have traditionally taken a very dim view of folks infringing on their business. (The limited supply and restricted access to Party Time Mentats created by The Museum of Friendship did not concern them much as it did not present them with competition.)
They also ship a significant share of the alcohol exported by Stillbourne – mostly to “dry” settlements on the outskirts of the NCR.
The McCoys are represented in the Union by Paddy McQuarrie, but they have operatives and dealers in every major (and several minor) settlements.