That isn't a problem in this video. If you go back to 15:15 you can hear original shots from the AR-15/M-16. the echo's you can clearly make out right after the round stops firing. The strikes are not near this location meaning I don't hear any strikes.
At 15:50 to 15:54 that is clearly a belt fed weapon firing.
22:32 then again 22:38 you can hear these belt fed weapon firing new rounds with a very faint echo. There is no striking sound from it. Then at 22:40 you hear the AR-15 again I couldn't make out an echo or where it strikes.
This video you can watch all the video's mixed where which they're all linked by time. You would have to know each one of these video's to know which one is firing. But this video you can hear what are fresh rounds and what are echos.
The video's with striking sounds are the ones closer to the stage..
https://www.youtube.com/watch?v=5vdeHMqCscs&t=308s
At 15:50 to 15:54 that is clearly a belt fed weapon firing.
I have heard lots of both, so please explain it to me.