liberdon.com is one of the many independent Mastodon servers you can use to participate in the fediverse.
Liberdon is an instance for libertarians, ancaps, anarchists, voluntaryists, agorists, etc to sound off without fear of reprisal. It was created in the wake of the Great Twitter Cullings of 2018.
For the individual who has never purchased a firearm before, or for someone who is doing the purchase solo, Sporting Systems out of Vancouver, WA has an excellent video on the process: