My own middle sized town has one dealer. The next big town has another. Cities will have a few dealers, and you can of course by online or by catalogue.
The main thing is that to own a rifle or shotgun, you need a licence. You have to apply, and the police can veto it if you have a criminal record or mental problems. And you have to prove you have proper storage ie a locked cabinet.
Do people have to have a reason for a fire arm? I read about a farmer that could not get a shotgun to protect his animals.