So I am a bit aware of the John Brown Gun Club and Socialist Rifle Association, but I am looking for more information.
Do any comrades here know of or are part of any gun groups for Marxists? Any information could be helpful, including about the two I mentioned. I've heard mixed reviews on both and would like it kind of straightened out. Also additional options or what have you would be nice.
I'm a provisional member of my local SRA chapter. It's not all Marxists, so you'd have to play nice with other ideologies there as well, but I like what I've experienced so far. So far I haven't seen any flame wars between ideologies on there. We all hate capitalism and imperialism. They're friendly people focused mainly on mutual aid while also being pro-gun. I haven't heard about any gun orgs that are strictly for Marxists.
The way it worked for me was I signed up for a paid membership online which got me access to the forums where I then posted an introduction about where I'm from. Someone should reach out to you on the forum to give you more info about the chapter you'd join. In my case they invited me to a discord room where you set up a time for a Jitsi video chat with members, after which they voted in private to approve me and I was then allowed into the rest of the discord channel where everyone communicates. I wish it wasn't on discord and would be on Matrix or something but they said it's the easiest to use and set up at the moment.
I am happy to hear that you did join and have been on-boarded! Your first paragraph sums up how things have been in my own experience. The org being a broad spectrum of the anti-capitalist left (imo) makes it a good place to meet and respectfully interact with comrades and learn more stuff you might not otherwise have.
My chapter primarily uses Signal for our primary communications and working groups. Though we have used Discord for chapter meetings (we have also used other options to see how well they handle video and audio). The real annoyance with Signal is that it can't do sub-chats/rooms like Discord or Slack. You can only "pin" like four group chats to the top. So as more working groups are made it becomes a "which chats should be pinned" issue.