This was often triggered by going into the menus and then backing out onto the game... The friends list remained as an overlay on the right side of the screen, so when you pulled the trigger you interacted with that menu, instead of your weapon, to make it disappear you just press options to go into start menu then circle to back out into the game and its fixed (on PS4).
A video would be great! This issue sounds really strange because it would be very obvious if it happened for everyone. And considering that all Playstation hardware is almost identical, I find it hard to understand how such an issue could happen. Do you have any other devices connected to your playstation? Maybe PSVR or some other third party controller?