Is there any other show on television that has so many deaths? It seems that in every episode Callen and Hanna, et al., blow away 3 or 4 terrorists, Russian Mafia, or foreign mercenaries. In the episode dealing with the Romanian crime family, the body count was close to 20.
In real life, law enforcement officers who kill someone are assigned to desk duty until the incident is investigated, and are sent to counseling. In this show, they don't have time to do any of that because they are too busy blowing away someone else.
It's also pretty unrealistic that they always win the gunfights, despite the fact that they are using handguns while the bad guys are almost always carrying automatic weapons (of course, that's not unique to this show. That's one of the enduring memes of television crime shows).