No internal gun in the T-2. We used an external 50 cal. gun pod with 100 rounds attached to one of the T-2 wing hardpoints. Of course in Advanced the F-9 Cougar had its own internal gun.There was no gun on the T-2 either (at least when I flew it....supposedly they had them way back in the day). The gun pattern was less about shooting and more about maneuvering and developing dynamic three dimensional SA.
The gun pattern was always wild, extremely demanding, and often dangerous.