Perhaps Gibbs has gone deep undercover in some criminal underworld that I’m guessing is somehow involved in that whole business he’s caught up in on the low with Tobias Fornell.
The NCIS team may not know Gibbs put these shots on McGee, but the people he could be working with would’ve certainly been suspicious had he whiffed a bunch of shots on an operative.
Not that knowing that would make McGee any happier about being shot by Gibbs, so I have to wonder if the shots were made in an effort to convince another group of his loyalty to them.