I want to learn about firearms, how to handle them, how to use them and how to talk about them without sounding like a moron for my worldbuilding and writing projects. I've considered options like talking to a professional, for example a hunter, policeman or soldier or going to a shooting range but these are to much effort in the beginning and would most likely be more beneficial once I got the basics down.
So what are great online sources (websites, YouTube channels) for learning about firearms and stuff surrounding them (like tactics, handling of guns,...)? I wouldn't mind books, but free sources would be preferable.
EDIT1: Optimally the sources should be understandable for an uninformed person. Yet if they lead to some higher level discussions of the subject I could read later to gain deeper insights this would be even better.