FW is a lot of hype and a fair amount of BS.
But let's put the blame where it belongs: the writers and director.
Mack is a SEAL, if he weren't you can be damn sure we would have heard about it by now. No one gets away with making a claim like that on national TV for years if it isn't true.
Also, Mack is read a script. As an actor, that's his job. That's it. He doesn't get to write the show. If he doesn't do what the director says, the simply fire him and find a new "cool guy" to fill his spot. All of the errors can be traced back to faulty writing, poor directing, and lazy editing. The actor is just reading the lines he's given. Being a former SEAL doesn't give an actor in a TV show the authority to tell the director in the middle of a shoot that the scene is all wrong and that he knows better. That's how you get fired. The same goes with all of the visual errors. For every shot that is seen one camera, dozens are probably filmed. Now the editors don't know jack about guns. They get raw footage, and trim and compile it into a show. A lot of times they will hack up scenes and cut and paste around to get the best looking product. To them, it doesn't have to be true or real, it just has to look good. They take the best shot of the round hitting the target with the best shot of Mack pulling the trigger. They don't have to be the same real shot. Crap like that doesn't matter to TV editors and producers. To us, it looks awkward and faked. But that doesn't mean Mack doesn't know what he's doing. It only means the editors don't care what's real or true. Just what looks good on TV.