Was in a chopper on a mission and I found some interesting things while looking at the guy in front of me (he had a silencer).
While the chopper flew around, the silencer of the guy actually rotated aroud the muzzle of his weapon. Maybe it's because of the heading changes of the chopper.
If the issue is reproducable (couldn't do it, because I don't have enough friends on arma 3 to fly the chopper and sit in it) it should be doable this way.
I will add some screenshots. {F18937} {F18938} {F18939} {F18940}