I've attached a video showing it, But to keep it simple, the T1S Cycler AR for the Terran Republic has an odd audio issue when I'm firing it indoors. this only started after the first patch, since originally all ARs had the same firing sound. Something to note, which I also mention in the video, I used to play PS2 on a different computer, and this issue happening, I thought it was just my machine, but a few weeks after launch I got a brand new system, and it's still here I had to stop using it because of the annoyance it caused me.
I wouldnt worry- playing as vanu- I get to hear - thump thump and Im dead before I get to flinch out of the way. The sounds on my end dont match up with when Im getting hit. your RoF is sick! =(