Naval Criminal Investigative Service,

That's been true in the past, but not so much this season. The premiere had to do with apprehending a terrorist--which is a primary duty of NCIS agents. The Queen's Gambit involved a Marine reservist--who is under NCIS jurisdiction. In Black Market, Sec Nav asked them to look into the murder of the Homeland agent (since they're under the Navy, they probably have to follow Sec Nav's orders). And Ghost Gun (this Sunday) involves a Navy Lt., I think. So, this season, the episodes are more focused on the military connection.

NCIS-LA should have been NCIS-SD... Since San Diego is a complete navy twn,, but Hollywood being Hollywood decided that filming would be easier in LA.. It is also easy to make every victim a navy person...

In real life they primarily investigate crimes committed by sailors, not against sailors. Most cases involve drug use and where sailors "borrow" government property.