Kid of a friend has a few suppressed guns. He’s deploying soon, plans to leave them with family.

Are there some kind of repercussions he ought to know about? Is there a proper way to do this?

If the NFA items are on a trust, anyone listed as a trustee is allowed to have access to them. If he filed as an individual, no one else is allowed to have access to them when he’s not around. Generally, that would mean having them locked up with him having the only key or combination.

Sounds good, he can simply leave them in the safe so long as he alone has access. That’s easy enough.