I've been hitting the range with a vengence lately. I experieced my 1st  malfunction with my OLY/DPMS 9MM. Went through 3 full mags on the 4th I had a double. Had the same thing happen again on the 5th mag. Ran 3 more after that without a problem. What do you think? I don't think it was a cook off. The gun was warm but not hot atleast not hot to me. Got 4-5k through this one possible worn FCG? I've been using Win white box for ammo.

Bob, check your FCG, specifically the disconnector.  I don't know about the Oly's, but the Colt's had a nasty habit of beating the crap out of the disconnector if the hammer wasn't swapped out to one of the 9mm models.  It will start doubling as it wears, and then go crazy when it breaks.

Don't ask me how I know this.

Thanks, I'll check it out. The  lower is a DPMS so who knows what quality the FCG is. I'll clean and check the gun over tonight. If I don't find anything I make another trip to the range. Either way I probably change out the FCG.

No need to change parts un-neededly..... re-time your disconnect for slight deeper engage to hammer shelf.   Should take you no more than 15 minute tops to complete the repair.