Gun raffle??? Ammunition? You can just sell guns at a swap meet in America? Ours are like full of old ladies selling soap and preserves and hardanger/crochet/knitted goods.

You totally can. I mean, it’s not like going to a swap meet in American means there aren’t old ladies selling knitted hats and jams or knock-off designer brands or oatmeal soap, it’s just that sometimes you can find guns and ammo, too.
But yeah, you can sell guns at swap meets. I believe the seller have to have proper permits and paperwork in order to do it legally, but the buyers don’t have to have a background check to get it in most states.