There's absolutely nothing wrong with the NRA rifle courses; the instructional courses are where the NRA really shines. The NRA as a 501(c)(4) is great. It's the NRA-ILA that's a steaming pile of shit.

The Socialist IRA is... Very dependent on the chapter. Some are fantastic, amazing groups. Some are very cliquish, and you're going to need to know your theory cold and never, ever voice any contrary opinions in order to get membership. (E.g., if I say that I think that come degree of professional policing is necessary, both because not all criminals are a product of material circumstances, and because 'community policing' can be the autobahn to vigilantism and night riders, that would get me thrown out of some chapters.)

There's also the Liberal Gun Club, which has some pretty decent people in it, but they're as scattered as the SocialistIRA is.

Operation Blazing Sword lists instructors that are willing to work with LGBTQ+ people; I'm on there for one of the states.

Appleseed events are a great way of learning the basics of rifle shooting over 2 days. Some of the history they teach as fact is highly suspect--it's more the American myth than American history---but they nominally keep contemporary politics out of it.