Random but it's tied to specific guns as in:1. Have a weapon hotkeyed (MP5K)
2. While switching to it after jogging/sprinting, hold RMB to aim
One M4/MP5/MP133 cannot produce sounds for other players,3. but if you drop it, andYour hand slot will now be locked
Will take another gun couple of times, you will start to make gun sounds again maybe evenbut you need to get the timing right (near the previous gun will make sounds again.beginning of the weapon swap animation)