Do it. You'd be amazed at how many people on the left have done so.
My husband and I did. We've trained extensively. I can guarantee you the other side knows how to use their weapons. It feels ridiculous, but I really think bad things are coming and we'd better be prepared.
I hope y'all laugh at me and call me ridiculous, but I'm truly concerned.
Yes, you should. And train with them. Find nearby like-minded people you can train with. You don't need many, but you really need to know how to use them.
As bad of a rep as they get, having an AR-15 is a really good idea. Readily available parts and ammo. Very easy to use. Easy to clean. Overall a good choice.