No Sound when firing M4

Commander class, used M4, drum mag, fore-grip, compensator no sound when firing.

That's a sound bug, it doesn't always happen but can do occasionally, and can happen to pretty much any weapon, it usually will go away at some point and in your next game, it will be fine, don't worry.

If it persists though, you can verify your game cache to make sure you're not missing any files.