PR6-308 was a planet in the Milky Way galaxy with a crystalline surface which held a Stargate. It was on this planet that an SG team first met with the alien Tlak'kahn while they were setting up an off-world base. The team, led by the shapeshifter Nephestis who was impersonating their leader Maj Bonner, walked straight into an ambush set by the Tlak'khan and most, if not all, were presumably killed. It was because of this that Bonner was branded a traitor, though he denied the action as he was asleep at the time of the ambush. (INF: "Decision")
It was during this mission the Captain Arnold Grimes was captured by the Sheftu, and was then taken to their homeworld so that Nephestis could pose as him and return to Earth. (INF: "Who Are You?")