Havent seen a good pic of the gun yet. I first said small caliber pistol, going by sound. But distance might account for that. .223/5.56 would be too small and too fast to catch on a photo unless it was the luckiest snap in history. So im not buying AR-15 till i see some proof.
Certainly plausible… If you go with 300 blk subsonic, it means you were suppressed…. also plausible… anon with the sound wave file did look like a first round pop. 2 and 3 were quieter…