I've let a ton of my friends handle, and shoot my suppressors, they are not in my trust, as long as you have your approved form 4, and you are present with your friend, you are good to go...
How many of you fellas have went to a machine gun shoot? You ever see one? I bet 99.9% of the fellas doing mag dumps on the owners platform aren't in any way shape or form affiliated with an NFA trust of that weapon.