In the US, it varies by State but Federal law says.anyone over the age of 18 can purchase a firearm as long as they are not a convicted felon, not subject to any restraining orders, and pass a firearm safety test / demonstration. You pay for the firearm, full out some sworn statements about not wanting to kill anyone, not a felon, etc. You then have to wait 10 days before you can handle the firearm and take it home.

The Justice Dept does a.background check during that 10 day waiting period. There are no limits on how much ammo you can buy or how many guns one can own. Anything made for civilian use that is not full auto capable is for sale. You can get a permit for just about any firearm though with proper training and credentials / requisites met.

Other countries? I'd like to hear about gun laws where youre from, everyone. Thanks!